Loans - Held for Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments in loans
Carrying Value	$ 20,528,925	$ 21,285,446
Face Amount	20,934,221	21,734,785
Credit loss allowances	(309,039)	(99,413)
Total net loans	20,219,886	$ 21,186,033	$ 18,413,649	$ 12,139,908
Commercial Portfolio Segment
Investments in loans
Carrying Value	15,377,364
Credit loss allowances	(298,775)
Infrastructure Portfolio Segment
Investments in loans
Carrying Value	2,505,924
Credit loss allowances	$ (10,264)
Residential Portfolio Segment
Investments in loans
Weighted Average Life	27 years 9 months 18 days	28 years 9 months 18 days
Loans held for investment
Investments in loans
Carrying Value	$ 17,883,288	$ 18,500,852
Face Amount	17,979,695	18,617,970
Credit loss allowances	(309,039)	(99,413)
Loans held for investment | Commercial Portfolio Segment
Investments in loans
Carrying Value	15,377,364	16,137,308
Face Amount	15,429,451	16,222,208
Credit loss allowances	(298,775)	(88,801)
Total net loans	15,078,589	16,048,507	13,450,198	9,583,949
Loans held for investment | Infrastructure Portfolio Segment
Investments in loans
Carrying Value	2,505,924	2,363,544
Face Amount	$ 2,550,244	$ 2,395,762
Weighted Average Life	3 years 10 months 24 days	3 years 10 months 24 days
Credit loss allowances	$ (10,264)	$ (10,612)
Total net loans	2,495,660	2,352,932	2,027,426	1,412,440
Loans held for investment | Residential Portfolio Segment
Investments in loans
Total net loans	$ 0	$ 0	59,225	90,684
Loans held for investment | Weighted-average | Infrastructure Portfolio Segment
Investments in loans
Weighted Average Coupon	9.50%	8.60%
Loans under fair value option
Investments in loans
Carrying Value	$ 2,645,637	$ 2,784,594
Face Amount	2,954,526	3,116,815
Credit loss allowances	0
Total net loans	2,645,637	2,784,594	$ 2,876,800	$ 1,052,835
Loans under fair value option | Residential, fair value option
Investments in loans
Carrying Value	2,604,594	2,763,458
Face Amount	2,909,126	3,092,915
Loans under fair value option | Commercial, fair value option
Investments in loans
Carrying Value	41,043	21,136
Face Amount	$ 45,400	$ 23,900
Weighted Average Life	5 years 2 months 12 days	8 years 7 months 6 days
Loans under fair value option | Weighted-average | Residential, fair value option
Investments in loans
Weighted Average Coupon	4.50%	4.50%
Loans under fair value option | Weighted-average | Commercial, fair value option
Investments in loans
Weighted Average Coupon	5.50%	5.70%
First Mortgages | Loans held for investment
Investments in loans
Carrying Value	$ 14,956,646	$ 15,562,452
Face Amount	$ 15,005,827	$ 15,648,358
Weighted Average Life	2 years 9 months 18 days	3 years 3 months 18 days
First Mortgages | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	9.00%	7.90%
Subordinated Mortgages | Loans held for investment
Investments in loans
Carrying Value	$ 76,560	$ 71,100
Face Amount	$ 76,882	$ 72,118
Weighted Average Life	2 years 2 months 12 days	3 years 2 months 12 days
Subordinated Mortgages | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	14.80%	13.60%
Mezzanine Loans
Investments in loans
Total net loans	$ 1,000,000	$ 1,300,000
Mezzanine Loans | Loans held for investment
Investments in loans
Carrying Value	273,146	445,363
Face Amount	$ 274,899	$ 442,339
Weighted Average Life	2 years 8 months 12 days	1 year 10 months 24 days
Mezzanine Loans | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	13.70%	12.90%
Other | Loans held for investment
Investments in loans
Carrying Value	$ 71,012	$ 58,393
Face Amount	$ 71,843	$ 59,393
Weighted Average Life	1 year 9 months 18 days	1 year 8 months 12 days
Other | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	9.60%	8.20%