Use of Special Purpose Entities and Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total residential whole loans	$ 5,600,000		$ 5,600,000	$ 5,300,000
Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Proceeds from issuance of debt		$ 1,853,408	2,511,087
Residential whole loans	2,300,000		2,300,000	1,800,000
Securitized debt	2,000,000		2,000,000	1,500,000
Asset-backed Securities, Securitized Loans and Receivables | Other Assets
Variable Interest Entity [Line Items]
Real estate owned at fair value	38,400		$ 38,400	$ 49,500
Senior Bonds
Variable Interest Entity [Line Items]
Proceeds from issuance of debt	805,900
Proceed from debt net of offering expenses and underwriting discount	$ 805,900