Repurchase Agreements (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements	$ 9,139,821	$ 7,879,087
MSR Asset Financing
Repurchase Agreement Counterparty [Line Items]
Cash collateral pledged	25,200	6,700
Repurchase agreement, borrowing commitment	75,000
Term Notes Backed by MSR-Related Collateral
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements	962,515	$ 474,127
Term Notes Backed by MSR-Related Collateral | Corporate Loan
Repurchase Agreement Counterparty [Line Items]
Repurchase agreements	$ 44,700
Minimum | MSR Asset Financing
Repurchase Agreement Counterparty [Line Items]
Line of credit facility, commitment fee rate	0.125%
Maximum | MSR Asset Financing
Repurchase Agreement Counterparty [Line Items]
Line of credit facility, commitment fee rate	0.50%