Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 2,353,959	$ 1,990,239
Other comprehensive income (loss) before reclassifications	(11,499)	583
Amounts reclassified from accumulated other comprehensive income (loss)	52	11
Total other comprehensive income (loss)	(11,447)	594
Balance at end of period	2,462,237	2,058,625
Unrealized Gains (Losses) on Short-term Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	21	0
Other comprehensive income (loss) before reclassifications	(59)	108
Amounts reclassified from accumulated other comprehensive income (loss)	27	0
Total other comprehensive income (loss)	(32)	108
Balance at end of period	(11)	108
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(4,218)	(4,820)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	25	11
Total other comprehensive income (loss)	25	11
Balance at end of period	(4,193)	(4,809)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	31,467	23,935
Other comprehensive income (loss) before reclassifications	(11,440)	475
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(11,440)	475
Balance at end of period	20,027	24,410
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	27,270	19,115
Total other comprehensive income (loss)	(11,447)	594
Balance at end of period	$ 15,823	$ 19,709