Other Comprehensive Income (Loss) Other Comprehensive Income Balance Components (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Foreign currency translation adjustment	$ 15,782	$ 0
Unrealized gain on post-retirement benefit obligations	20,055	20,055
Unrealized gain (loss) on marketable securities	0	3
Unrealized gain (loss) on hedging activities, net of noncontrolling interest	(4,397)	(9,446)
Accumulated other comprehensive income (loss)	$ 31,440	$ 10,612