General and Administrative Expenses, Loan Acquisition Costs, and Other Expenses - Components of General and Administrative Expenses and Other Expenses (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
	Oct. 15, 2019	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Fixed compensation expense		$ 10,103		$ 9,391	$ 36,605	$ 26,740
Variable compensation expense		5,882		3,489	9,171	11,356
Equity compensation expense		2,639		3,155	7,896	10,132
Acquisition-related equity compensation expense		1,212		0	3,636	0
Systems and consulting		2,145		3,230	7,752	7,594
Office costs		1,859		1,517	5,854	4,406
Accounting and legal		1,601		1,767	6,605	3,852
Corporate costs		831		482	2,128	1,701
Other operating expenses		1,358		1,868	5,185	4,941
Total General and Administrative Expenses		27,630		24,899	84,832	70,722
Commissions		879		659	3,027	1,432
Underwriting costs		771		1,074	3,289	3,184
Transfer and holding costs		508		183	1,400	891
Total Loan Acquisition Costs		2,158		1,916	7,716	5,507
Goodwill impairment expense		0	$ 89,000	0	88,675	0
Amortization of purchase-related intangible assets		3,873		1,897	12,052	4,608
Contingent consideration expense		135		236	581	547
Other		3,780		398	2,978	866
Total Other Expenses		7,788		2,531	104,286	6,021
Total General and Administrative Expenses, Loan Acquisition Costs, and Other Expenses		37,576		$ 29,346	196,834	$ 82,250
Variable compensation expense		3,000			3,000
Cash Based Retention Award
Business Acquisition [Line Items]
Cash-based retention awards granted		$ 8,000			$ 8,000
Variable compensation expense, term		3 years
Long Term Relative TSR Performance Vesting Cash Awards
Business Acquisition [Line Items]
Variable compensation expense, service period		3 years
CoreVest
Business Acquisition [Line Items]
Restricted stock awards (in shares)	588,260
Restricted stock awards	$ 10,000
Contingent consideration performance term	2 years