Investments in Servicing Related Assets, Summary (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2021	Dec. 31, 2020
Servicing Asset [Abstract]
Unpaid principal balance		$ 21,523,383	$ 21,641,277
Cost basis		210,032	316,314
Carrying value	[1]	$ 211,995	$ 174,414
Weighted average coupon		3.63%	3.92%
Weighted average maturity	[2]	26 years 4 months 24 days	26 years 3 months 18 days
Year to date changes in fair value recorded in other income (loss)		$ 1,963	$ (141,900)
Mortgage Servicing Rights (MSRs) [Member]
Servicing Asset [Abstract]
Unpaid principal balance		21,523,383	21,641,277
Cost basis	[3]	210,032	316,314
Carrying value	[1]	$ 211,995	$ 174,414
Weighted average coupon		3.63%	3.92%
Weighted average maturity	[2]	26 years 4 months 24 days	26 years 3 months 18 days
Year to date changes in fair value recorded in other income (loss)		$ 1,963	$ (141,900)

[1] See Note 9 regarding the estimation of fair value, which approximates carrying value for all pools.

[2] Weighted average maturity of the underlying residential mortgage loans in the pool is based on the unpaid principal balance.

[3] MSR cost basis consists of the carrying value of the prior period, adjusted for any purchases and sales of the underlying mortgage loans.