| Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] | Period [Axis] |
|---|
2016-01-01 - 2016-12-31 |
|---|
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] | |
Change in Benefit Obligation | The funded status and amounts recognized in the 2016 and 2015 consolidated balance sheets, as measured on December 31, 2016 and 2015, respectively, for the Retirement Account and Postretirement Plans were as follows. | | | | | | | | | | | | | | | Retirement Account Plan | Postretirement Plan | Retirement Account Plan | Postretirement Plan | | 2016 | 2016 | 2015 | 2015 | | ($ in Thousands) | Change in Fair Value of Plan Assets | | | | | Fair value of plan assets at beginning of year | $ | 289,599 |
| $ | — |
| $ | 303,496 |
| $ | — |
| Actual return on plan assets | 17,097 |
| — |
| 495 |
| — |
| Employer contributions | — |
| 248 |
| — |
| 264 |
| Gross benefits paid | (10,978 | ) | (248 | ) | (14,392 | ) | (264 | ) | Fair value of plan assets at end of year* | $ | 295,718 |
| $ | — |
| $ | 289,599 |
| $ | — |
| Change in Benefit Obligation | | | | | Net benefit obligation at beginning of year | $ | 171,783 |
| $ | 3,436 |
| $ | 171,333 |
| $ | 3,578 |
| Service cost | 6,780 |
| — |
| 11,257 |
| — |
| Interest cost | 7,121 |
| 142 |
| 6,617 |
| 141 |
| Plan amendments | (823 | ) | (936 | ) | — |
| — |
| Actuarial (gain) loss | 2,942 |
| 9 |
| (3,032 | ) | (19 | ) | Gross benefits paid | (10,978 | ) | (248 | ) | (14,392 | ) | (264 | ) | Net benefit obligation at end of year* | $ | 176,825 |
| $ | 2,403 |
| $ | 171,783 |
| $ | 3,436 |
| Funded (unfunded) status | $ | 118,893 |
| $ | (2,403 | ) | $ | 117,816 |
| $ | (3,436 | ) | Noncurrent assets | 118,893 |
| — |
| 117,816 |
| — |
| Current liabilities | — |
| (215 | ) | — |
| (274 | ) | Noncurrent liabilities | — |
| (2,188 | ) | — |
| (3,162 | ) | Asset (Liability) Recognized in the Consolidated Balance Sheets | $ | 118,893 |
| $ | (2,403 | ) | $ | 117,816 |
| $ | (3,436 | ) |
| | * | The fair value of the plan assets represented 167% and 169% of the net benefit obligation of the pension plan at December 31, 2016 and 2015, respectively. |
|
AOCI Components | Amounts recognized in accumulated other comprehensive loss, net of tax, as of December 31, 2016 and 2015 follow. | | | | | | | | | | | | | | | Retirement Account Plan | Postretirement Plan | Retirement Account Plan | Postretirement Plan | | 2016 | 2016 | 2015 | 2015 | | ($ in Thousands) | Prior service cost | $ | (342 | ) | $ | (580 | ) | $ | 122 |
| $ | — |
| Net actuarial loss | 35,443 |
| 79 |
| 32,879 |
| 73 |
| Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive loss | $ | 35,101 |
| $ | (501 | ) | $ | 33,001 |
| $ | 73 |
|
|
Changes in OCI | Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) (“OCI”), net of tax, in 2016 and 2015 were as follows. | | | | | | | | | | | | | | | | | | Retirement Account
Plan | | Postretirement
Plan | | Retirement Account
Plan | | Postretirement
Plan | | 2016 | | 2016 | | 2015 | | 2015 | | ($ in Thousands) | Net gain (loss) | $ | (6,132 | ) | | $ | (9 | ) | | $ | (17,911 | ) | | $ | 19 |
| Amortization of prior service cost | (73 | ) | | — |
| | 50 |
| | — |
| Amortization of actuarial gain | 2,115 |
| | — |
| | 2,256 |
| | — |
| Plan amendments | 823 |
| | 936 |
| | — |
| | — |
| Income tax (expense) benefit | 1,168 |
| | (353 | ) | | 5,880 |
| | (7 | ) | Total Recognized in OCI | $ | (2,099 | ) | | $ | 574 |
| | $ | (9,725 | ) | | $ | 12 |
|
|
Net period benefit cost for the pension and postretirement plans | The components of net periodic benefit cost for the Retirement Account Plan and Postretirement Plans for 2016, 2015, and 2014 were as follows. | | | | | | | | | | | | | | | | | | | | | Retirement Account
Plan | Postretirement
Plan | Retirement Account
Plan | Postretirement
Plan | Retirement Account
Plan | Postretirement
Plan | | 2016 | 2016 | 2015 | 2015 | 2014 | 2014 | | | | ($ in Thousands) | | | Service cost | $ | 6,780 |
| $ | — |
| $ | 11,257 |
| $ | — |
| $ | 11,058 |
| $ | — |
| Interest cost | 7,121 |
| 142 |
| 6,617 |
| 141 |
| 7,132 |
| 150 |
| Expected return on plan assets | (20,287 | ) | — |
| (21,438 | ) | — |
| (19,922 | ) | — |
| Amortization of: | | | | | | | Prior service cost | (73 | ) | — |
| 50 |
| — |
| 58 |
| — |
| Actuarial (gain) loss | 2,115 |
| — |
| 2,256 |
| — |
| 1,384 |
| (35 | ) | Total net pension cost | $ | (4,344 | ) | $ | 142 |
| $ | (1,258 | ) | $ | 141 |
| $ | (290 | ) | $ | 115 |
|
|
Weighted Average Benefit Assumptions | | | | | | | | | | | | Retirement Account Plan | Postretirement Plan | Retirement Account Plan | Postretirement Plan | | 2016 | 2016 | 2015 | 2015 | Weighted average assumptions used to determine benefit obligations: | | | | | Discount rate | 4.10 | % | 4.10 | % | 4.30 | % | 4.30 | % | Rate of increase in compensation levels | 4.00 | % | NA |
| 4.00 | % | NA |
| Weighted average assumptions used to determine net periodic benefit costs: | | | | | Discount rate | 4.30 | % | 4.30 | % | 4.00 | % | 4.00 | % | Rate of increase in compensation levels | 4.00 | % | NA |
| 4.00 | % | NA |
| Expected long-term rate of return on plan assets | 7.00 | % | NA |
| 7.50 | % | NA |
|
|
Plan Asset Allocation Percentages | The asset allocation for the Retirement Account Plan as of the December 31, 2016 and 2015 measurement dates, respectively, by asset category were as follows. | | | | | | | Asset Category | 2016 | | 2015 | Equity securities | 60 | % | | 60 | % | Fixed income securities | 39 | % | | 40 | % | Other | 1 | % | | — | % | Total | 100 | % | | 100 | % |
|
Pension Plan Investments | Based on these inputs, the following table summarizes the fair value of the Retirement Account Plan’s investments as of December 31, 2016 and 2015. | | | | | | | | | | | | | | | | | | | | Fair Value Measurements Using | | December 31, 2016 | | Level 1 | | Level 2 | | Level 3 | | ($ in Thousands) | Retirement Account Plan Investments: | | | | | | | | Money market account | $ | 3,624 |
| | $ | 3,624 |
| | $ | — |
| | $ | — |
| Common /collective trust funds | 126,741 |
| | 126,741 |
| | — |
| | — |
| Mutual funds | 165,353 |
| | 165,353 |
| | — |
| | — |
| Total Retirement Account Plan Investments | $ | 295,718 |
| | $ | 295,718 |
| | $ | — |
| | $ | — |
| | | | Fair Value Measurements Using | | December 31, 2015 | | Level 1 | | Level 2 | | Level 3 | | ($ in Thousands) | Retirement Account Plan Investments: | | | | | | | | Money market account | $ | 481 |
| | $ | 481 |
| | $ | — |
| | $ | — |
| Common /collective trust funds | 120,136 |
| | 120,136 |
| | — |
| | — |
| Mutual funds | 168,982 |
| | 168,982 |
| | — |
| | — |
| Total Retirement Account Plan Investments | $ | 289,599 |
| | $ | 289,599 |
| | $ | — |
| | $ | — |
|
|
Expected Benefit Payments | The projected benefit payments for the Retirement Account and Postretirement Plans at December 31, 2016, reflecting expected future services, were as follows. The projected benefit payments were calculated using the same assumptions as those used to calculate the benefit obligations listed above. | | | | | | | | | | Retirement Account Plan | | Postretirement Plan | | ($ in Thousands) | Estimated future benefit payments: | | | | 2017 | $ | 14,829 |
| | $ | 215 |
| 2018 | 14,538 |
| | 199 |
| 2019 | 14,169 |
| | 179 |
| 2020 | 13,815 |
| | 177 |
| 2021 | 13,651 |
| | 174 |
| 2022-2026 | 71,433 |
| | 815 |
|
|
One Percentage Point Change in Assumed Health Care Cost | A one percentage point change in the assumed health care cost trend rate would have the following effect. | | | | | | | | | | | | | | | 2016 | 2015 | | 100 bp Increase | 100 bp Decrease | 100 bp Increase | 100 bp Decrease | | ($ in Thousands) | Effect on total of service and interest cost | $ | 7 |
| $ | (6 | ) | $ | 15 |
| $ | (13 | ) | Effect on postretirement benefit obligation | $ | 173 |
| $ | (149 | ) | $ | 357 |
| $ | (310 | ) |
|