Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 919,907	$ 717,043
Gross Unrealized Gains	245	411
Gross Unrealized Losses	(243)	(120)
Debt Securities, Available-for-sale	919,909	717,334
Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	337,964	137,783
Debt Securities, Available-for-sale	337,964	137,783
Cash equivalents [Member] \| Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	165,667	40,027
Debt Securities, Available-for-sale	165,667	40,027
Cash equivalents [Member] \| Time deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	31,588	36,756
Debt Securities, Available-for-sale	31,588	36,756
Cash equivalents [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	131,000	61,000
Debt Securities, Available-for-sale	131,000	61,000
Cash equivalents [Member] \| Government and corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	9,709
Debt Securities, Available-for-sale	9,709
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	476,298	442,277
Gross Unrealized Gains	235	259
Gross Unrealized Losses	(171)	(63)
Debt Securities, Available-for-sale	476,362	442,473
Short-term investments [Member] \| Time deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	31,192	28,302
Debt Securities, Available-for-sale	31,192	28,302
Short-term investments [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	252,500	264,000
Gross Unrealized Gains	9	12
Gross Unrealized Losses	(70)	(19)
Debt Securities, Available-for-sale	252,439	263,993
Short-term investments [Member] \| Government and corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	192,606	149,975
Gross Unrealized Gains	226	247
Gross Unrealized Losses	(101)	(44)
Debt Securities, Available-for-sale	192,731	150,178
Long-term investments [Member] \| Government and corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	105,645	136,983
Gross Unrealized Gains	10	152
Gross Unrealized Losses	(72)	(57)
Debt Securities, Available-for-sale	$ 105,583	$ 137,078

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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