Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accumulated Other Comp Inc (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 2,911,816
Other comprehensive income (loss) before reclassifications	(9,343)
Amounts reclassified from accumulated other comprehensive income (loss)	151
Adoption of ASU No. 2016-01	(9,144)
Other comprehensive income (loss), net of tax	(18,336)	$ 783
Balance at the end of the period	2,709,608
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	11,185	(12,119)
Other comprehensive income (loss) before reclassifications		659
Amounts reclassified from accumulated other comprehensive income (loss)		124
Other comprehensive income (loss), net of tax	(18,336)	783
Balance at the end of the period	(7,151)	(11,336)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(922)	(1,296)
Amounts reclassified from accumulated other comprehensive income (loss)	109	93
Other comprehensive income (loss), net of tax	109	93
Balance at the end of the period	(813)	(1,203)
Unrealized gains (losses) on available-for-sale securities
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	9,144	14,235
Other comprehensive income (loss) before reclassifications		(3,201)
Adoption of ASU No. 2016-01	(9,144)
Other comprehensive income (loss), net of tax	(9,144)	(3,201)
Balance at the end of the period		11,034
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(4,111)	(3,760)
Amounts reclassified from accumulated other comprehensive income (loss)	42	31
Other comprehensive income (loss), net of tax	42	31
Balance at the end of the period	(4,069)	(3,729)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	7,074	(21,298)
Other comprehensive income (loss) before reclassifications	(9,343)	3,860
Other comprehensive income (loss), net of tax	(9,343)	3,860
Balance at the end of the period	$ (2,269)	$ (17,438)