New Accounting Standards - Compensation – Retirement Benefits (Topic 715) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	$ (53,941)	$ (172,659)	$ (90,060)	$ (191,043)
Other (income) expense, net	$ 11,001	3,288	$ 7,569	(7,893)
ASU 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income		(100)		200
Other (income) expense, net		$ 100		$ (200)