Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment $ / shares	Sep. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jan. 01, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Equity, Class of Treasury Stock [Line Items]
Adjustment for allowance for credit losses	$ 777,415	$ 798,520	$ 777,415	$ 798,520	$ 753,596	$ 721,265		$ 816,805	$ 771,418	$ 751,065	$ 733,228
Minimum distribution percentage to qualify for REIT taxation status			90.00%
Income tax expense	$ 178	2,094	$ (2,466)	3,701
Number of reportable segments | segment			4
Preferred stock, par value per share (in dollars per share) | $ / shares	$ 0.01		$ 0.01					$ 0.01
Convertible preferred stock purchase agreements | Convertible preferred stock
Equity, Class of Treasury Stock [Line Items]
Preferred stock, par value per share (in dollars per share) | $ / shares	0.01		0.01
Dividend payment terms stock price per share (in usd per share) | $ / shares	$ 16.67		$ 16.67
Conversion basis of preferred stock (in shares)	299.2		299.2
Terms of liquidity event period			6 years
Building and Improvements
Equity, Class of Treasury Stock [Line Items]
Acquired finite-lived intangible assets, weighted average useful life			40 years
Furniture and fixtures
Equity, Class of Treasury Stock [Line Items]
Acquired finite-lived intangible assets, weighted average useful life			15 years
Accumulated Deficit
Equity, Class of Treasury Stock [Line Items]
Adjustment for allowance for credit losses	$ (123,460)	$ (89,369)	$ (123,460)	$ (89,369)	$ (129,289)	$ (121,500)		$ (85,968)	$ (95,597)	$ (91,825)	$ (94,266)
Accounting standards update 2016-13
Equity, Class of Treasury Stock [Line Items]
Cumulative effect of new accounting principle in period of adoption, effect per share (in dollars per share) | $ / shares							$ 0.18
Cumulative effect of new accounting principle in period of adoption, effect on total commitments, percent							0.27%
Transition Adjustment
Equity, Class of Treasury Stock [Line Items]
Adjustment for allowance for credit losses								(7,761)
Transition Adjustment | Accumulated Deficit
Equity, Class of Treasury Stock [Line Items]
Adjustment for allowance for credit losses							$ 7,800	$ (7,761)