Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities
Net loss	$ (321,143)	$ (109,613)	$ (18,527)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	64,907	46,906	14,564
Stock-based compensation	68,257	54,722	36,973
Amortization of debt discount and issuance costs	6,137	4,989	12,038
Non-cash lease expense	16,234	11,630	9,204
Impairment costs	1,136	0	2,063
Loss on conversions of convertible senior notes	0	0	4,634
Net loss (gain) on IRLCs, forward sales commitments, and loans held for sale	14,427	815	(1,921)
Change in fair value of mortgage servicing rights, net	(801)	0	0
Gain on extinguishment of convertible senior notes	(57,193)	0	0
Other	3,791	(4,227)	(349)
Change in assets and liabilities:
Accounts receivable, net	24,411	(7,149)	(35,496)
Inventory	243,948	(309,063)	25,432
Prepaid expenses and other assets	(5,904)	(12,248)	2,333
Accounts payable	(2,472)	3,059	2,086
Accrued and other liabilities, deferred tax liabilities, and payroll tax liabilities, noncurrent	(46,454)	25,791	39,092
Lease liabilities	(18,452)	(13,268)	(11,312)
Origination of mortgage servicing rights	(3,140)	0	0
Proceeds from sale of mortgage servicing rights	1,662	0	0
Origination of loans held for sale	(3,949,442)	(986,982)	(677,310)
Proceeds from sale of loans originated as held for sale	4,000,582	993,070	657,763
Net cash provided by (used in) operating activities	40,491	(301,568)	61,267
Investing activities
Purchases of property and equipment	(21,531)	(27,492)	(14,686)
Purchases of investments	(182,466)	(146,274)	(198,172)
Sales of investments	17,545	98,687	7,887
Maturities of investments	99,455	106,773	147,852
Cash paid for acquisition, net of cash, cash equivalents, and restricted cash acquired	(97,341)	(608,000)	0
Net cash used in investing activities	(184,338)	(576,306)	(57,119)
Financing activities
Proceeds from the issuance of convertible preferred stock, net of issuance costs	0	0	39,801
Proceeds from the issuance of common stock, net of issuance costs	0	0	69,701
Proceeds from the issuance of common stock pursuant to employee equity plans	11,528	22,772	21,072
Tax payments related to net share settlements on restricted stock units	(7,498)	(27,066)	(16,852)
Borrowings from warehouse credit facilities	3,938,265	942,993	662,278
Repayments to warehouse credit facilities	(3,989,407)	(948,979)	(644,551)
Borrowings from secured revolving credit facility	565,334	624,828	89,619
Repayments to secured revolving credit facility	(765,114)	(448,996)	(70,115)
Cash paid for secured revolving credit facility issuance costs	(733)	(527)	(4)
Proceeds from issuance of convertible senior notes, net of issuance costs	0	561,529	647,486
Purchases of capped calls related to convertible senior notes	0	(62,647)	0
Conversions of convertible senior notes	0	(2,159)	(108,061)
Principal payments under finance lease obligations	(855)	(796)	(221)
Repurchases of convertible senior notes	(83,614)	0	0
Other financing payables	0	(10,611)	4,074
Net cash (used in) provided by financing activities	(332,094)	650,341	694,227
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(94)	(6)	(3)
Net change in cash, cash equivalents, and restricted cash	(476,035)	(227,539)	698,372
Cash, cash equivalents, and restricted cash:
Beginning of period	718,281	945,820	247,448
End of period	242,246	718,281	945,820
Supplemental disclosure of cash flow information
Cash paid for interest	20,107	7,592	4,958
Non-cash transactions
Stock-based compensation capitalized in property and equipment	3,660	4,059	2,348
Property and equipment additions in accounts payable and accrued liabilities	99	659	1,682
Leasehold improvements paid directly by lessor	118	1,334	37
Issuance of common stock for repurchases and conversions of convertible senior notes	0	0	98,397
Reconciliation of cash, cash equivalents, and restricted cash
Cash and cash equivalents	239,840	591,003	925,276
Restricted cash	2,406	127,278	20,544
Total cash, cash equivalents, and restricted cash	$ 242,246	$ 718,281	$ 945,820