Fair Value Measurements - Fair Value of Financial Assets by Level (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	$ 689,663	$ 689,663	$ 397,261
Marketable Debt Securities	2,447,459	2,447,459	2,322,469
Marketable Securities	2,479,290	2,479,290	2,352,022
Total Financial Assets	3,169,809	3,169,809	2,753,554
Commercial paper
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	88,960	88,960	0
Certificates of deposits
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	6,998	6,998	10,492
U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	783,513	783,513	993,955
Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	1,051,495	1,051,495	1,113,134
Agency securities
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	523,491	523,491	215,380
Marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Marketable Equity Securities	24,833	24,833	19,061
Unrealized gain on equity investment	11,300	5,800
Initial cost for equity investment	3,000	3,000
Money market funds - restricted
Assets, Fair Value Disclosure [Abstract]
Other Assets	856	856	4,271
Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	574,779	574,779	322,294
Commercial paper
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	5,422
U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	99,898	99,898	51,986
Agency securities
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	14,986	14,986	17,559
Level I
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	674,677	674,677	374,280
Marketable Securities	808,346	808,346	1,013,016
Total Financial Assets	1,483,879	1,483,879	1,391,567
Level I | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level I | Certificates of deposits
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level I | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	783,513	783,513	993,955
Level I | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level I | Agency securities
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level I | Marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Marketable Equity Securities	24,833	24,833	19,061
Level I | Money market funds - restricted
Assets, Fair Value Disclosure [Abstract]
Other Assets	856	856	4,271
Level I | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	574,779	574,779	322,294
Level I | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level I | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	99,898	99,898	51,986
Level I | Agency securities
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level II
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	14,986	14,986	22,981
Marketable Securities	1,670,944	1,670,944	1,339,006
Total Financial Assets	1,685,930	1,685,930	1,361,987
Level II | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	88,960	88,960	0
Level II | Certificates of deposits
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	6,998	6,998	10,492
Level II | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level II | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	1,051,495	1,051,495	1,113,134
Level II | Agency securities
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	523,491	523,491	215,380
Level II | Marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Marketable Equity Securities	0	0	0
Level II | Money market funds - restricted
Assets, Fair Value Disclosure [Abstract]
Other Assets	0	0	0
Level II | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level II | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	5,422
Level II | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level II | Agency securities
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	14,986	14,986	17,559
Level III
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Marketable Securities	0	0	0
Total Financial Assets	0	0	0
Level III | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level III | Certificates of deposits
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level III | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level III | Corporate bonds
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level III | Agency securities
Assets, Fair Value Disclosure [Abstract]
Marketable Debt Securities	0	0	0
Level III | Marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Marketable Equity Securities	0	0	0
Level III | Money market funds - restricted
Assets, Fair Value Disclosure [Abstract]
Other Assets	0	0	0
Level III | Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level III | Commercial paper
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level III | U.S. government notes
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	0	0	0
Level III | Agency securities
Assets, Fair Value Disclosure [Abstract]
Cash Equivalents	$ 0	$ 0	$ 0