CASH EQUIVALENTS AND MARKETABLE SECURITIES - Summary of Cash Equivalents and Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents, at carrying value, total	$ 178,872	$ 131,329
Available-for-sale securities, amortized cost	286,138	560,575
Available-for-sale securities, gross unrealized gains	11	86
Available-for-sale securities, gross unrealized (Losses)	(304)	(37)
Available-for-sale securities, estimated fair value	285,845	560,624
Total cash equivalents and available-for-sale securities, amortized cost	406,057	613,740
Total cash equivalents and available-for-sale securities, gross unrealized gains	11	86
Total cash equivalents and available-for-sale securities, gross unrealized (losses)	(304)	(37)
Total cash equivalents and available-for-sale securities, estimated fair value	405,764	613,789
Money market funds
ASSETS
Cash and cash equivalents, at carrying value, total	119,919	53,165
Cash equivalents, gross unrealized gains	0	0
Cash and cash equivalents accumulated gross unrealized loss before tax	0	0
Cash equivalents, estimated fair value	119,919	53,165
Cash equivalents:
ASSETS
Cash and cash equivalents, at carrying value, total	119,919	53,165
Cash equivalents, gross unrealized gains	0	0
Cash and cash equivalents accumulated gross unrealized loss before tax	0	0
Cash equivalents, estimated fair value	119,919	53,165
U.S. government-sponsored entity debt securities
ASSETS
Available-for-sale securities, amortized cost	30,700	257,284
Available-for-sale securities, gross unrealized gains	1	19
Available-for-sale securities, gross unrealized (Losses)	(87)	(5)
Available-for-sale securities, estimated fair value	30,614	257,298
Commercial paper securities
ASSETS
Available-for-sale securities, amortized cost	105,792	213,500
Available-for-sale securities, gross unrealized gains	7	41
Available-for-sale securities, gross unrealized (Losses)	(42)	(8)
Available-for-sale securities, estimated fair value	105,757	213,533
Corporate debt securities
ASSETS
Available-for-sale securities, amortized cost	33,723	59,575
Available-for-sale securities, gross unrealized gains	1	16
Available-for-sale securities, gross unrealized (Losses)	(42)	(17)
Available-for-sale securities, estimated fair value	33,682	59,574
Certificates of deposit
ASSETS
Available-for-sale securities, amortized cost	45,116	12,311
Available-for-sale securities, gross unrealized gains	1	0
Available-for-sale securities, gross unrealized (Losses)	(26)	0
Available-for-sale securities, estimated fair value	45,091	12,311
Asset-backed securities
ASSETS
Available-for-sale securities, amortized cost	70,807	17,905
Available-for-sale securities, gross unrealized gains	1	10
Available-for-sale securities, gross unrealized (Losses)	(107)	(7)
Available-for-sale securities, estimated fair value	$ 70,701	$ 17,908

Cash and cash equivalents accumulated gross unrealized gain before tax.

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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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