Equity and Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 1,403,404	$ 1,217,536
Total other comprehensive income (loss)	$ (815)	$ 26,978	13,001	46,325
Ending balance	1,526,954	1,270,000	1,526,954	1,270,000
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			1,138	(1,425)
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income (loss)			248	47
Total other comprehensive income (loss)			248	47
Ending balance	1,386	(1,378)	1,386	(1,378)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			5,124	(659)
Other comprehensive income (loss) before reclassifications			12,753	46,278
Amounts reclassified from accumulated other comprehensive income (loss)			0	0
Total other comprehensive income (loss)			12,753	46,278
Ending balance	17,877	45,619	17,877	45,619
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			6,262	(2,084)
Other comprehensive income (loss) before reclassifications			12,753	46,278
Amounts reclassified from accumulated other comprehensive income (loss)			248	47
Total other comprehensive income (loss)			13,001	46,325
Ending balance	$ 19,263	$ 44,241	$ 19,263	$ 44,241