Fair Value Measurements - Financial Assets and Liabilities Subject to Fair Value Measurements (Details) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020 |
Financial instruments carried at fair value (liability positions): | | |
Long-term contingent consideration | $ (187,300) | $ (189,600) |
Recurring Basis | | |
Financial instruments carried at fair value (asset positions): | | |
Derivative asset current, foreign currency forward contracts | 9,545 | 0 |
Derivative asset noncurrent, foreign currency forward contracts | 1,378 | 0 |
Total financial assets | 4,331,883 | 3,811,763 |
Financial instruments carried at fair value (liability positions): | | |
Derivative liability current, foreign currency forward contracts | (20,361) | (59,184) |
Long-term contingent consideration | (187,300) | (189,600) |
Derivative liability noncurrent, foreign currency forward contracts | (206) | (4,283) |
Total financial liabilities | (207,867) | (253,067) |
Recurring Basis | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Derivative asset current, foreign currency forward contracts | 0 | 0 |
Derivative asset noncurrent, foreign currency forward contracts | 0 | 0 |
Total financial assets | 3,766,273 | 3,236,766 |
Financial instruments carried at fair value (liability positions): | | |
Derivative liability current, foreign currency forward contracts | 0 | 0 |
Long-term contingent consideration | 0 | 0 |
Derivative liability noncurrent, foreign currency forward contracts | 0 | 0 |
Total financial liabilities | 0 | 0 |
Recurring Basis | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Derivative asset current, foreign currency forward contracts | 9,545 | 0 |
Derivative asset noncurrent, foreign currency forward contracts | 1,378 | 0 |
Total financial assets | 565,610 | 574,997 |
Financial instruments carried at fair value (liability positions): | | |
Derivative liability current, foreign currency forward contracts | (20,361) | (59,184) |
Long-term contingent consideration | 0 | 0 |
Derivative liability noncurrent, foreign currency forward contracts | (206) | (4,283) |
Total financial liabilities | (20,567) | (63,467) |
Recurring Basis | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Derivative asset current, foreign currency forward contracts | 0 | 0 |
Derivative asset noncurrent, foreign currency forward contracts | 0 | 0 |
Total financial assets | 0 | 0 |
Financial instruments carried at fair value (liability positions): | | |
Derivative liability current, foreign currency forward contracts | 0 | 0 |
Long-term contingent consideration | (187,300) | (189,600) |
Derivative liability noncurrent, foreign currency forward contracts | 0 | 0 |
Total financial liabilities | (187,300) | (189,600) |
Recurring Basis | Money market funds | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 3,674,645 | 3,141,053 |
Recurring Basis | Money market funds | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 3,674,645 | 3,141,053 |
Recurring Basis | Money market funds | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 0 | 0 |
Recurring Basis | Money market funds | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 0 | 0 |
Recurring Basis | Commercial paper | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 2,000 | 0 |
Marketable securities | 275,842 | 163,268 |
Recurring Basis | Commercial paper | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 0 | 0 |
Marketable securities | 0 | 0 |
Recurring Basis | Commercial paper | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 2,000 | 0 |
Marketable securities | 275,842 | 163,268 |
Recurring Basis | Commercial paper | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Cash and cash equivalents | 0 | 0 |
Marketable securities | 0 | 0 |
Recurring Basis | Corporate equity securities | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 154,095 | 195,781 |
Recurring Basis | Corporate equity securities | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 13,033 | 15,650 |
Recurring Basis | Corporate equity securities | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 141,062 | 180,131 |
Recurring Basis | Corporate equity securities | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | U.S. Treasury securities | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 16,220 | 0 |
Recurring Basis | U.S. Treasury securities | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 16,220 | 0 |
Recurring Basis | U.S. Treasury securities | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | U.S. Treasury securities | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | Government-sponsored enterprise securities | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 62,375 | 80,063 |
Recurring Basis | Government-sponsored enterprise securities | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 62,375 | 80,063 |
Recurring Basis | Government-sponsored enterprise securities | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | Government-sponsored enterprise securities | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | Corporate debt securities | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 135,783 | 231,598 |
Recurring Basis | Corporate debt securities | Level 1 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 0 | 0 |
Recurring Basis | Corporate debt securities | Level 2 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | 135,783 | 231,598 |
Recurring Basis | Corporate debt securities | Level 3 | | |
Financial instruments carried at fair value (asset positions): | | |
Marketable securities | $ 0 | $ 0 |