Loans - Held for Investment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Investments in loans
Carrying Value	$ 21,397,743	$ 21,285,446
Face Amount	21,831,800	21,734,785
Credit loss allowances	(134,430)	(99,413)
Total net loans	21,263,313	$ 21,186,033	$ 18,937,769	$ 18,413,649
Commercial Portfolio Segment
Investments in loans
Carrying Value	16,213,072
Credit loss allowances	(118,479)
Infrastructure Portfolio Segment
Investments in loans
Carrying Value	2,373,782
Credit loss allowances	$ (15,951)
Residential Portfolio Segment
Investments in loans
Weighted Average Life	28 years 6 months	28 years 9 months 18 days
Loans held for investment
Investments in loans
Carrying Value	$ 18,586,854	$ 18,500,852
Face Amount	18,691,798	18,617,970
Credit loss allowances	(134,430)	(99,413)
Loans held for investment | Commercial Portfolio Segment
Investments in loans
Carrying Value	16,213,072	16,137,308
Face Amount	16,286,098	16,222,208
Credit loss allowances	(118,479)	(88,801)
Total net loans	16,094,593	16,048,507	14,061,518	13,450,198
Loans held for investment | Infrastructure Portfolio Segment
Investments in loans
Carrying Value	2,373,782	2,363,544
Face Amount	$ 2,405,700	$ 2,395,762
Weighted Average Life	3 years 10 months 24 days	3 years 10 months 24 days
Credit loss allowances	$ (15,951)	$ (10,612)
Total net loans	2,357,831	2,352,932	2,136,118	2,027,426
Loans held for investment | Residential Portfolio Segment
Investments in loans
Total net loans	$ 0	$ 0	55,621	59,225
Loans held for investment | Weighted-average | Infrastructure Portfolio Segment
Investments in loans
Weighted Average Coupon	9.10%	8.60%
Loans under fair value option
Investments in loans
Carrying Value	$ 2,810,889	$ 2,784,594
Face Amount	3,140,002	3,116,815
Credit loss allowances	0
Total net loans	2,810,889	2,784,594	$ 2,684,512	$ 2,876,800
Loans under fair value option | Residential, fair value option
Investments in loans
Carrying Value	2,733,358	2,763,458
Face Amount	3,054,552	3,092,915
Loans under fair value option | Commercial, fair value option
Investments in loans
Carrying Value	77,531	21,136
Face Amount	$ 85,450	$ 23,900
Weighted Average Life	9 years 6 months	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	6.00%	5.70%
First mortgages | Loans held for investment
Investments in loans
Carrying Value	$ 15,610,218	$ 15,562,452
Face Amount	$ 15,684,751	$ 15,648,358
Weighted Average Life	1 year 7 months 6 days	1 year 8 months 12 days
First mortgages | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	8.40%	7.90%
Subordinated mortgages | Loans held for investment
Investments in loans
Carrying Value	$ 72,379	$ 71,100
Face Amount	$ 73,244	$ 72,118
Weighted Average Life	1 year 6 months	1 year 9 months 18 days
Subordinated mortgages | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	14.10%	13.60%
Mezzanine Loans
Investments in loans
Total net loans	$ 1,300,000	$ 1,300,000
Mezzanine Loans | Loans held for investment
Investments in loans
Carrying Value	472,404	445,363
Face Amount	$ 469,176	$ 442,339
Weighted Average Life	1 year 1 month 6 days	1 year
Mezzanine Loans | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	13.20%	12.90%
Other | Loans held for investment
Investments in loans
Carrying Value	$ 58,071	$ 58,393
Face Amount	$ 58,927	$ 59,393
Weighted Average Life	1 year 2 months 12 days	1 year 4 months 24 days
Other | Loans held for investment | Weighted-average
Investments in loans
Weighted Average Coupon	8.20%	8.20%