Supplemental Balance Sheet, Income Statement and Cash Flow Information - Accumulated Other Comp Inc (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 1,982,811
Other comprehensive income (loss), net of tax	664	$ 17,537	$ (40,510)
Balance at the end of the period	1,151,384	1,982,811
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(11,788)	(29,325)
Other comprehensive income (loss) before reclassifications	435	16,943
Amounts reclassified from accumulated other comprehensive income (loss)	229	594
Other comprehensive income (loss), net of tax	664	17,537
Balance at the end of the period	(11,124)	(11,788)	(29,325)
Gains (losses) on cash flow hedges
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(65)	(492)
Amounts reclassified from accumulated other comprehensive income (loss)	67	427
Other comprehensive income (loss), net of tax	67	427
Balance at the end of the period	2	(65)	(492)
Defined benefit pension plan items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(3,778)	(3,945)
Amounts reclassified from accumulated other comprehensive income (loss)	162	167
Other comprehensive income (loss), net of tax	162	167
Balance at the end of the period	(3,616)	(3,778)	(3,945)
Foreign currency items
Changes in accumulated other comprehensive income (loss)
Balance at the beginning of the period	(7,945)	(24,888)
Other comprehensive income (loss) before reclassifications	435	16,943
Other comprehensive income (loss), net of tax	435	16,943
Balance at the end of the period	$ (7,510)	$ (7,945)	$ (24,888)