Borrowings (Schedule of Debt Repayments) (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Debt Instrument [Line Items]
Expected principal repayments related to consolidated residential mortgage loan securitizations	$ 1,014,000
Repurchase Agreements
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months	2,490,745
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	226,893
2020 Scheduled Repayment of Principal	0
2021 Scheduled Repayment of Principal	0
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	0
Total Scheduled Repayment of Principal	2,717,638
Other Secured Borrowings
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months	402,196
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	249,345
2020 Scheduled Repayment of Principal	178,815
2021 Scheduled Repayment of Principal	130,488
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	100,922
Total Scheduled Repayment of Principal	1,061,766
Senior Notes
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months	86,000
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	0
2020 Scheduled Repayment of Principal	0
2021 Scheduled Repayment of Principal	0
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	0
Total Scheduled Repayment of Principal	86,000
Total
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months	2,978,941
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	476,238
2020 Scheduled Repayment of Principal	178,815
2021 Scheduled Repayment of Principal	130,488
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	100,922
Total Scheduled Repayment of Principal	$ 3,865,404