Investments and Fair Value Measurements - Summary Of Assets And Liabilities That Are Measured At Fair Value On A Recurring And Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Marketable securities:
Debt securities	$ 5,728,778	$ 5,729,892
Total	7,470,209	6,703,423
Level 1
Marketable securities:
Total	1,736,573	968,685
Level 2
Marketable securities:
Total	5,733,636	5,734,738
Level 3
Marketable securities:
Total	0	0
U.S. Treasury securities
Marketable securities:
Debt securities	5,728,778	5,729,892
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Money market funds
Cash and cash equivalents:
Cash and cash equivalents	1,730,569	945,330
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Money market funds \| Level 1
Cash and cash equivalents:
Cash and cash equivalents	1,730,569	945,330
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Money market funds \| Level 2
Cash and cash equivalents:
Cash and cash equivalents	0	0
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Money market funds \| Level 3
Cash and cash equivalents:
Cash and cash equivalents	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| U.S. Treasury securities
Marketable securities:
Debt securities	5,728,778	5,729,892
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| U.S. Treasury securities \| Level 1
Marketable securities:
Debt securities	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| U.S. Treasury securities \| Level 2
Marketable securities:
Debt securities	5,728,778	5,729,892
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| U.S. Treasury securities \| Level 3
Marketable securities:
Debt securities	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| Publicly-traded equity securities
Marketable securities:
U.S. treasury securities	6,004	23,355
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| Publicly-traded equity securities \| Level 1
Marketable securities:
U.S. treasury securities	6,004	23,355
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| Publicly-traded equity securities \| Level 2
Marketable securities:
U.S. treasury securities	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesCurrent \| Publicly-traded equity securities \| Level 3
Marketable securities:
U.S. treasury securities	0	0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Certificates of deposit
Prepaid expenses and other current assets and other assets:
Certificates of deposit	4,858	4,846
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Certificates of deposit \| Level 1
Prepaid expenses and other current assets and other assets:
Certificates of deposit	0	0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Certificates of deposit \| Level 2
Prepaid expenses and other current assets and other assets:
Certificates of deposit	4,858
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Certificates of deposit \| Level 3
Prepaid expenses and other current assets and other assets:
Certificates of deposit	0	0
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Certificates of deposit
Prepaid expenses and other current assets and other assets:
Certificates of deposit	4,858	4,846
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Certificates of deposit \| Level 1
Prepaid expenses and other current assets and other assets:
Certificates of deposit	0	0
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Certificates of deposit \| Level 2
Prepaid expenses and other current assets and other assets:
Certificates of deposit	4,858	4,846
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Certificates of deposit \| Level 3
Prepaid expenses and other current assets and other assets:
Certificates of deposit	$ 0	$ 0