Summary of Significant Accounting Policies - Narrative (Details)			3 Months Ended		6 Months Ended
	Feb. 01, 2019	Jan. 31, 2018	Jun. 30, 2020 USD ($) variable_interest_entity	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) variable_interest_entity loan	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Conversion of stock, conversion ratio	1	1
Cash equivalents			$ 0		$ 0		$ 0
Impairment of operating real estate			25,935,000	$ 10,124,000	30,061,000	$ 10,124,000
Income tax benefit (expense)			(2,102,000)	133,000	(3,813,000)	502,000
Real estate securities, available for sale
Variable Interest Entity [Line Items]
Impairment loss on securities			29,200,000		$ 29,200,000
Core
Variable Interest Entity [Line Items]
Loans held-for-sale, number of loans | loan					1
Impairment of operating real estate			0	0	$ 0	0
Income tax benefit (expense)			$ (2,101,000)	$ (359,000)	$ (2,264,000)	$ 1,629,000
Unconsolidated VIEs | Third Party Joint Venture Partners | Minimum
Variable Interest Entity [Line Items]
Ownership percentage by noncontrolling owners (in percentage)			3.50%		3.50%
Unconsolidated VIEs | Third Party Joint Venture Partners | Maximum
Variable Interest Entity [Line Items]
Ownership percentage by noncontrolling owners (in percentage)			20.00%		20.00%
Primary Beneficiary
Variable Interest Entity [Line Items]
Number of investing VIEs | variable_interest_entity			2		2