Contingent Liabilities - Other (Details) - Threatened Litigation - USD ($)		1 Months Ended			6 Months Ended
	Jul. 13, 2016	Jul. 29, 2016	Dec. 31, 2014	Sep. 30, 2013	Jun. 26, 2016	Jun. 14, 2016
Loss Contingencies [Line Items]
Demand for payment			$ 34,000,000	$ 26,000,000
Decline in contributions, percent (more than)				70.00%
Overstatement of pension withdrawal obligation						$ 7,500,000
Partial pension withdrawal arbitration liability					$ 11,300,000
Partial pension withdrawal contingent loss, minimum					0
Partial pension withdrawal contingent loss, maximum					10,000,000
Payments made in accordance with ERISA					15,100,000
Payments made in current period					3,500,000
Subsequent Event
Loss Contingencies [Line Items]
Overpayment reimbursed from the Fund in connection with partial withdrawal obligation	$ 5,000,000	$ 5,000,000
Initial Assessment
Loss Contingencies [Line Items]
Payments made in accordance with ERISA					9,900,000
Revised Assessment
Loss Contingencies [Line Items]
Payments made in accordance with ERISA					$ 5,200,000