Schedule I — Condensed Financial Information of Registrant - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from Operating activities:
Net loss	$ (334,620)	$ (443,286)	$ (704,471)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred income	(3,383)	(2,602)	(521)
Share-based compensation	79,634	61,302	40,714
Loss from fair value changes of equity investment of readily determinable fair value	(2,789)	8,952	14,617
Changes in operating assets and liabilities:
Prepayments and other current assets	12,246	(19,258)	(7,086)
Other current liabilities	19,810	7,392	30,142
Net cash provided by (used in) operating activities	(198,178)	(367,642)	(549,231)
Cash flows from investing activities
Purchase of short-term investments	(134,000)	(260,274)	(445,000)
Proceeds from maturity of short-term investments	117,700	705,274	743,902
Purchase of investment in equity investee	0	0	(30,000)
Net cash (used in) provided by investing activities	(10,776)	420,016	249,957
Cash flows from financing activities
Proceeds from exercises of stock options	2,369	5,870	7,417
Proceeds from issuance of ordinary shares upon public offerings	0	0	818,875
Payment of public offering costs	0	0	(1,837)
Taxes paid related to settlement of equity awards	(8,802)	(7,600)	(4,253)
Net cash (used in) provided by financing activities	(6,433)	(1,730)	820,202
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(2,622)	(6,274)	1,116
Net (decrease) increase in cash, cash equivalents and restricted cash	(218,009)	44,370	522,044
Cash, cash equivalents and restricted cash — beginning of the year	1,009,273	964,903	442,859
Cash, cash equivalents and restricted cash — end of the year	791,264	1,009,273	964,903
Parent Company
Cash flows from Operating activities:
Net loss	(334,620)	(443,286)	(704,471)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred income	0	(234)	(312)
Share-based compensation	3,217	3,724	3,435
Equity in loss of subsidiaries	352,449	427,514	676,099
Loss from fair value changes of equity investment of readily determinable fair value	(2,789)	8,952	14,617
Changes in operating assets and liabilities:
Prepayments and other current assets	2,780	(7,839)	(439)
Other current liabilities	(379)	1,648	(376)
Net cash provided by (used in) operating activities	20,658	(9,521)	(11,447)
Cash flows from investing activities
Purchase of short-term investments	0	(260,274)	(445,000)
Proceeds from maturity of short-term investments	0	705,274	743,902
Purchase of investment in equity investee	0	0	(30,000)
Investment in subsidiaries	(392,893)	(80,942)	(884,342)
Net cash (used in) provided by investing activities	(392,893)	364,058	(615,440)
Cash flows from financing activities
Proceeds from exercises of stock options	2,369	5,870	7,418
Proceeds from issuance of ordinary shares upon public offerings	0	0	818,875
Payment of public offering costs	0	0	(1,692)
Taxes paid related to settlement of equity awards	(8,802)	(7,600)	(4,253)
Net cash (used in) provided by financing activities	(6,433)	(1,730)	820,348
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	0	0	773
Net (decrease) increase in cash, cash equivalents and restricted cash	(378,668)	352,807	194,234
Cash, cash equivalents and restricted cash — beginning of the year	944,649	591,842	397,608
Cash, cash equivalents and restricted cash — end of the year	$ 565,981	$ 944,649	$ 591,842