Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income before noncontrolling interests	$ 160,942	$ 211,834	$ 114,311
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Gains attributable to the fair value of future servicing rights, net of guaranty obligation	(172,401)	(193,886)	(192,825)
Change in the fair value of premiums and origination fees	(5,037)	5,781	(10,796)
Amortization and depreciation	142,134	131,246	111,427
Stock compensation-equity and liability classified	23,959	21,134	18,477
Provision (benefit) for credit losses	808	(243)	(612)
Deferred tax expense (benefit)	17,483	(30,961)	37,595
Originations of loans held for sale	(15,153,003)	(17,018,424)	(12,040,559)
Sales of loans to third parties	15,050,932	17,937,915	12,697,209
Amortization of deferred loan fees and costs	(1,742)	(2,298)	(1,578)
Amortization of debt issuance costs and debt discount	7,509	4,886	5,581
Origination fees received from loans held for investment	3,968	1,109	2,104
Cash paid to settle risk-sharing obligations			(1,613)
Changes in:
Servicing fees and other receivables	(4,532)	(12,234)	(5,744)
Other assets	(6,861)	(7,064)	(916)
Accounts payable and other liabilities	(13,957)	22,866	22,035
Performance deposits from borrowers	13,874	(4,019)	5,368
Net cash provided by (used in) operating activities	64,076	1,067,642	759,464
Cash flows from investing activities
Capital expenditures	(4,722)	(5,207)	(2,478)
Proceeds from the sale of equity-method investments	4,993
Purchase of pledged available-for-sale securities	(98,442)	(6,966)
Funding of preferred equity investments	(41,100)	(16,884)	(24,835)
Repayments of preferred equity investments	82,819
Capital invested in the Interim Program JV, net	(4,137)	(6,342)
Net cash paid to increase ownership interest in a previously held equity method investment			(1,058)
Acquisitions, net of cash received	(53,249)	(15,000)	(6,350)
Purchase of mortgage servicing rights	(1,814)	(7,781)	(43,097)
Originations of loans held for investment	(597,889)	(183,916)	(414,763)
Principal collected on loans held for investment upon payoff	161,303	219,516	425,820
Sales of loans held for investment		119,750
Net cash provided by (used in) investing activities	(552,238)	97,170	(66,761)
Cash flows from financing activities
Borrowings (repayments) of warehouse notes payable, net	139,298	(955,040)	(649,845)
Borrowings of interim warehouse notes payable	145,043	140,341	325,828
Repayments of interim warehouse notes payable	(61,050)	(237,912)	(355,738)
Repayments of note payable	(166,223)	(1,104)	(1,104)
Borrowings of note payable	298,500
Secured borrowings	70,052
Proceeds from issuance of common stock	8,949	3,013	3,765
Repurchase of common stock	(68,832)	(34,899)	(12,893)
Cash dividends paid	(31,445)
Payment of contingent consideration	(5,150)
Debt issuance costs	(7,312)	(3,890)	(3,630)
Distributions to noncontrolling interest holders			(5)
Net cash provided by (used in) financing activities	321,830	(1,089,491)	(693,622)
Net increase (decrease) in cash, cash equivalents, restricted cash, and restricted cash equivalents (NOTE 2)	(166,332)	75,321	(919)
Cash, cash equivalents, restricted cash, and restricted cash equivalents at beginning of period	286,680	211,359	212,278
Total of cash, cash equivalents, restricted cash, and restricted cash equivalents at end of period	120,348	286,680	211,359
Supplemental Disclosure of Cash Flow Information:
Cash paid to third parties for interest	56,430	56,267	39,311
Cash paid for income taxes	$ 45,728	$ 45,524	$ 34,432