Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0000017843 (http://www.sec.gov/CIK)

Debt Disclosure [Abstract]	Period [Axis]
	2015-07-01 - 2016-06-30
Debt Disclosure [Abstract]
Schedule of long-term debt outstanding	Long-term debt outstanding as of June 30, 2016 and 2015 consisted of the following:      June 30, ($ in millions)   2016   2015 Medium-term notes, Series B at 6.97% to 7.10% due from April 2018 to May 2018 (face value of $55.0 million at June 30, 2016 and 2015)   $ 55.0   $ 55.0 Senior unsecured notes, 5.20% due July 2021 (face value of $250.0 million at June 30, 2016 and 2015)   257.8   250.5 Senior unsecured notes, 4.45% due March 2023 (face value of $300.0 million at June 30, 2016 and 2015)   298.5   298.3 Total   611.3   603.8 Long-term debt, net of current portion   $ 611.3   $ 603.8