Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 540,613	$ 1,082,070	$ 888,549
Other comprehensive income (loss):
Unrecognized gains (losses) on equity investments		0	5,120	0
Reclassification adjustment for write down of equity investment		(5,120)	0	0
Unrecognized gains (losses) on cash flow hedges		2	1,414	(766)
Unrecognized actuarial gain/(loss)		269	190	246
Unrecognized gains (losses) on foreign currency translation		85,263	(85,557)	(46,679)
Total other comprehensive income		80,414	(78,833)	(47,199)
Total comprehensive income		621,027	1,003,237	841,350
Less : Total comprehensive income (loss) attributable to noncontrolling interests	[1]	40,187	6,722	(31,166)
Comprehensive income attributable to controlling interests		$ 580,840	$ 996,515	$ 872,516

[1] Includes amounts attributable to redeemable noncontrolling interests.