Securitizations and Variable Interest Entities - Unconsolidated VIEs with Significant Continuing Involvement (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total assets of consolidated VIEs	$ 4,900,319	$ 1,863,293
Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of consolidated VIEs	1,386,279	3,233,416
Net Assets	75,333	174,891
Total exposure	75,333	174,891
Available-for-sale Securities [Member] | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of consolidated VIEs	58,177	142,026
Total exposure	58,177	142,026
Other Assets | Unconsolidated VIEs
Variable Interest Entity [Line Items]
Total assets of consolidated VIEs	17,156	32,865
Total exposure	$ 17,156	$ 32,865