Supplemental Balance Sheet and Income Statement Information - Accumulated Other Comp Inc (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 2,700,850
Adoption of ASU No. 2016-01	0
Other comprehensive income (loss), net of tax	9,338	$ (18,336)
Balance at the end of the period	2,586,335
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(29,325)	11,185
Other comprehensive income (loss) before reclassifications	9,190	(9,343)
Amounts reclassified from accumulated other comprehensive income (loss)	148	151
Adoption of ASU No. 2016-01		(9,144)
Other comprehensive income (loss), net of tax	9,338	(18,336)
Balance at the end of the period	(19,987)	(7,151)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(492)	(922)
Amounts reclassified from accumulated other comprehensive income (loss)	106	109
Other comprehensive income (loss), net of tax	106	109
Balance at the end of the period	(386)	(813)
Unrealized gains (losses) on available-for-sale securities
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period		9,144
Adoption of ASU No. 2016-01		(9,144)
Other comprehensive income (loss), net of tax		(9,144)
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(3,945)	(4,111)
Amounts reclassified from accumulated other comprehensive income (loss)	42	42
Other comprehensive income (loss), net of tax	42	42
Balance at the end of the period	(3,903)	(4,069)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(24,888)	7,074
Other comprehensive income (loss) before reclassifications	9,190	(9,343)
Other comprehensive income (loss), net of tax	9,190	(9,343)
Balance at the end of the period	$ (15,698)	$ (2,269)