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Network
1131 - Disclosure - Other Comprehensive Income - Summary of Change in Accumulated Other Comprehensive Income (Loss) (Detail)
(http://www.progbank.com/taxonomy/role/DisclosureOtherComprehensiveIncomeSummaryOfChangeInAccumulatedOtherComprehensiveIncomeLoss)
Table(Implied)
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0000736772 (http://www.sec.gov/CIK)
Equity [Abstract]Period [Axis]
2016-01-01 - 2016-12-31
2015-01-01 - 2015-12-31
2014-01-01 - 2014-12-31
Equity [Abstract]
 
 
 
Unrealized gains (losses) on securities available for sale, Beginning Balance
3,529,000  
2,736,000  
(7,636,000) 
Unrealized gains (losses) on securities available for sale, Increase (Decrease)
(2,136,000) 
793,000  
10,372,000  
Unrealized gains (losses) on securities available for sale, Ending Balance
1,393,000  
 
3,529,000  
 
2,736,000  
 
Unrealized gain (loss) on postretirement benefits plan, Increase (Decrease)
(1,153,000) 
(1,063,000) 
(1,084,000) 
Unrealized gain (loss) on postretirement benefits plan, Ending Balance
(64,000) 
(90,000) 
21,000  
Unrealized gain (loss) on postretirement benefits plan, Ending Balance
(1,217,000) 
 
(1,153,000) 
 
(1,063,000) 
 
Unrealized gain (loss) on interest rate swap, Beginning Balance
(477,000) 
(614,000) 
(725,000) 
Unrealized gain (loss) on interest rate swap, Increase (Decrease)
180,000  
137,000  
111,000  
Unrealized gain (loss) on interest rate swap, Ending Balance
(297,000) 
 
(477,000) 
 
(614,000) 
 
Total, Beginning Balance
1,899,000  
1,059,000  
(9,445,000) 
Total, Increase (Decrease)
(2,020,000) 
840,000  
10,504,000  
Total, Ending Balance
(121,000) 
 
1,899,000  
 
1,059,000