Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 319,361	$ 251,723	$ 339,523
Other comprehensive income (loss):
Change in foreign currency translation adjustment	0	(21,804)	8,482
Available for sale securities:
Change in net unrealized losses	(2,080)	(911)	(985)
Less: reclassification adjustment for net losses (gains) included in net income	170	(1,317)	(203)
Net change (net of tax effect)	(1,910)	(2,228)	(1,188)
Gain (loss) on pension liability	4,083	(6,512)	2,500
Cash flow hedges:
Change in unrealized losses	(6,937)	(9,074)	(67)
Less: reclassification adjustment for net losses (gains) included in net income	13,027	(2,123)	2,929
Net change (net of tax effect)	6,090	(11,197)	2,862
Other comprehensive income (loss)	8,263	(41,741)	12,656
Comprehensive income	$ 327,624	$ 209,982	$ 352,179