Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (834,032)	$ (712,735)
Amortization	10,269	9,682
Other current period change	43,543	(29,600)
Ending balance	(780,220)	(732,653)
Currency Translation Adjustments and Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(206,610)	(136,020)
Other current period change	43,343	(18,578)
Ending balance	(163,267)	(154,598)
Net Actuarial Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(620,292)	(576,993)
Amortization	10,159	9,754
Other current period change	200	(5,597)
Ending balance	(609,933)	(572,836)
Prior Service (Cost)/ Credit
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(7,130)	278
Amortization	110	(72)
Other current period change	0	(5,425)
Ending balance	$ (7,020)	$ (5,219)