UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Tax (benefit) associated with gain (loss) on components of foreign currency translation	$ (16,023)	$ (19,733)
Net unrealized (losses) gains on marketable securities, before tax	(1,800)	353,800
Tax exempt net unrealized (losses) gains on marketable securities, before tax, in the Netherlands	32,400	323,700
Taxable net unrealized (losses) gains on marketable securities, before tax	(34,200)	30,100
Tax (benefit) associated with gain (loss) on marketable securities	(1,428)	7,855
Reclassification of net unrealized gains on marketable equity securities to retained earnings, tax/(benefit)	57,597	0
Tax and Customs Administration, Netherlands
Tax (benefit) associated with gain (loss) on marketable securities	(8,500)	7,900
Domestic Tax Authority [Member]
Tax (benefit) associated with gain (loss) on marketable securities	7,100	0
Currency translation adjustment on deemed repatriation tax liability [Member]
Tax (benefit) associated with gain (loss) on components of foreign currency translation	10,500	0
Net Investment Hedging [Member]
Tax (benefit) associated with gain (loss) on components of foreign currency translation	$ (26,500)	$ (19,700)