Loans - Activity in Portfolio (Details) $ in Thousands	1 Months Ended					12 Months Ended
	Dec. 31, 2023 USD ($) power_plant	May 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	May 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Dec. 31, 2023 USD ($) power_plant	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Apr. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						$ 99,413
Credit loss (reversal) provision, net						232,712	$ 49,049	$ 4,633
Credit loss allowance at the end of the period	$ 309,039		$ 99,413			309,039	99,413
Activity in loan portfolio
Balance at the beginning of the period						21,186,033	18,413,649	12,139,908
Acquisitions/originations/additional funding						3,474,242	10,178,734	13,990,579
Capitalized interest						125,747	124,150	119,136
Basis of loans sold						(866,104)	(4,253,551)	(4,176,868)
Loan maturities/principal repayments						(3,647,171)	(2,258,630)	(4,197,809)
Discount accretion/premium amortization						67,112	62,557	57,948
Changes in fair value						62,702	(346,222)	69,050
Foreign currency translation gain (loss), net						153,472	(306,946)	(72,130)
Credit loss provision, net						(232,712)	(49,049)	(4,633)
Loan foreclosure, equity control and conversion to equity interest						(102,774)	(290,311)	(36,308)
Transfer to/from other asset/liability classifications or between segments						(661)	(88,348)	524,776
Balance at the end of the period	20,219,886		21,186,033			20,219,886	21,186,033	18,413,649
Carrying Value	20,528,925		21,285,446			20,528,925	21,285,446
Texas Mezzanine Borrower
Activity in loan portfolio
Net consideration transferred				$ 50,200
90 days or greater past due | Non-Credit Deterioration
Activity in loan portfolio
Carrying Value	$ 488,900					$ 488,900
Past due loan converted to equity interests										$ 7,300
Chicago
Activity in allowance for loan losses
Number of natural gas power plants | power_plant	2					2
Unfunded commitments
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						$ 9,873	6,837	6,070
Credit loss (reversal) provision, net						1,055	3,036	767
Credit loss allowance at the end of the period	$ 10,928		9,873			10,928	9,873	6,837
Unfunded commitments	1,346,445					1,346,445
Activity in loan portfolio
Credit loss provision, net						(1,055)	(3,036)	(767)
HTM Preferred Intrests
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						0	0	0
Credit loss (reversal) provision, net						1,548	0	0
Credit loss allowance at the end of the period	1,548		0			1,548	0	0
Unfunded commitments	8,282					8,282
Activity in loan portfolio
Credit loss provision, net						(1,548)	0	0
CMBS
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						52	0	0
Credit loss (reversal) provision, net						22	52	0
Credit loss allowance at the end of the period	74		52			74	52	0
Unfunded commitments	34,743					34,743
Activity in loan portfolio
Credit loss provision, net						(22)	(52)	0
Residential Loans | Commercial and Residential Lending Segment
Activity in loan portfolio
Face amount						0	1,057,013	216,827
Residential Loans | Agency-Eligible Residential Loan | Commercial and Residential Lending Segment
Activity in loan portfolio
Face amount					$ 745,000		745,000
Contingency expense							88,400
Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						99,413
Credit loss allowance at the end of the period	309,039		99,413			309,039	99,413
Activity in loan portfolio
Carrying Value	17,883,288		18,500,852			17,883,288	18,500,852
Total loans held-for-investment | First mortgage loan participation
Activity in loan portfolio
Carrying Value	14,956,646		15,562,452			14,956,646	15,562,452
Loans under fair value option
Activity in allowance for loan losses
Credit loss (reversal) provision, net						0	0	0
Credit loss allowance at the end of the period	0					0
Activity in loan portfolio
Balance at the beginning of the period						2,784,594	2,876,800	1,052,835
Acquisitions/originations/additional funding						757,355	4,634,722	5,351,034
Capitalized interest						172	508	2,650
Basis of loans sold						(813,104)	(4,216,618)	(3,856,736)
Loan maturities/principal repayments						(185,884)	(193,105)	(352,711)
Discount accretion/premium amortization						0	0	504
Changes in fair value						62,702	(343,053)	67,864
Foreign currency translation gain (loss), net						0	0	0
Credit loss provision, net						0	0	0
Loan foreclosure, equity control and conversion to equity interest						(929)	0	0
Transfer to/from other asset/liability classifications or between segments						40,731	25,340	611,360
Balance at the end of the period	2,645,637		2,784,594			2,645,637	2,784,594	2,876,800
Carrying Value	2,645,637		2,784,594			2,645,637	2,784,594
Funded commitments
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						99,413	67,270	77,444
Credit loss (reversal) provision, net						232,712	49,049	4,633
Charge-offs						(23,086)	(16,906)	(14,807)
Transfers								0
Credit loss allowance at the end of the period	309,039		99,413			309,039	99,413	67,270
Charge-offs						23,086	16,906	14,807
Activity in loan portfolio
Credit loss provision, net						(232,712)	(49,049)	(4,633)
Commercial Portfolio Segment
Activity in allowance for loan losses
Credit loss allowance at the end of the period	298,775					298,775
Activity in loan portfolio
Carrying Value	15,377,364					15,377,364
Commercial Portfolio Segment | Credit deteriorated
Activity in allowance for loan losses
Credit loss allowance at the end of the period	4,925					4,925
Activity in loan portfolio
Carrying Value	4,925					4,925
Commercial Portfolio Segment | Senior Loans | Chicago
Activity in loan portfolio
Loan foreclosure, equity control and conversion to equity interest		$ (41,100)
Commercial Portfolio Segment | Senior Loans | California
Activity in loan portfolio
Loan converted to equity interest			223,800
Commercial Portfolio Segment | Senior Loans | New York | 90 days or greater past due | Non-Credit Deterioration
Activity in loan portfolio
Carrying Value	9,200					9,200
Commercial Portfolio Segment | Mortgage Loan And Mezzanine Loan | Pacific Northwest
Activity in loan portfolio
Loan foreclosure, equity control and conversion to equity interest	(60,800)
Commercial Portfolio Segment | Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						88,801
Credit loss (reversal) provision, net						222,266	42,201	(7,947)
Credit loss allowance at the end of the period	298,775		88,801			298,775	88,801
Activity in loan portfolio
Balance at the beginning of the period						16,048,507	13,450,198	9,583,949
Acquisitions/originations/additional funding						1,713,979	4,882,414	7,822,441
Capitalized interest						125,057	121,500	112,178
Basis of loans sold						(53,000)	(10,109)	(307,454)
Loan maturities/principal repayments						(2,596,738)	(1,764,638)	(3,508,969)
Discount accretion/premium amortization						53,418	52,939	52,416
Changes in fair value						0	0	0
Foreign currency translation gain (loss), net						152,869	(304,051)	(71,419)
Credit loss provision, net						(222,266)	(42,201)	7,947
Loan foreclosure, equity control and conversion to equity interest						(101,845)	(273,929)	(36,308)
Transfer to/from other asset/liability classifications or between segments						(41,392)	(63,616)	(204,583)
Balance at the end of the period	15,078,589		16,048,507			15,078,589	16,048,507	13,450,198
Carrying Value	15,377,364		16,137,308			15,377,364	16,137,308
Commercial Portfolio Segment | Funded commitments
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						88,801	46,600	69,611
Credit loss (reversal) provision, net						222,266	42,201	(7,947)
Charge-offs						(12,292)	0	(14,807)
Transfers								(257)
Credit loss allowance at the end of the period	298,775		88,801			298,775	88,801	46,600
Charge-offs						12,292	0	14,807
Activity in loan portfolio
Credit loss provision, net						(222,266)	(42,201)	7,947
Commercial Portfolio Segment | Funded commitments | Chicago
Activity in allowance for loan losses
Charge-offs								(7,000)
Charge-offs								7,000
Commercial Portfolio Segment | Funded commitments | New York
Activity in allowance for loan losses
Charge-offs								(7,800)
Charge-offs								7,800
Commercial Portfolio Segment | Unfunded Loan Commitment, Loans Held-For-Investment
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						9,749	6,692	5,258
Credit loss (reversal) provision, net						(1,007)	3,057	1,434
Credit loss allowance at the end of the period	8,742		9,749			8,742	9,749	6,692
Unfunded commitments	1,237,874					1,237,874
Activity in loan portfolio
Credit loss provision, net						1,007	(3,057)	(1,434)
Infrastructure Portfolio Segment
Activity in allowance for loan losses
Credit loss allowance at the end of the period	10,264					10,264
Activity in loan portfolio
Carrying Value	2,505,924					2,505,924
Infrastructure Portfolio Segment | Infrastructure Loans | Chicago | Credit deteriorated
Activity in allowance for loan losses
Charge-offs						(10,800)
Charge-offs						10,800
Infrastructure Portfolio Segment | Senior Loans | Chicago | Credit deteriorated
Activity in loan portfolio
Carrying Value	4,900					4,900
Infrastructure Portfolio Segment | Senior Loans | Massachusetts
Activity in loan portfolio
Loan converted to equity interest			16,400
Infrastructure Portfolio Segment | Total loans held-for-investment
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						10,612
Credit loss (reversal) provision, net						10,446	6,848	12,580
Credit loss allowance at the end of the period	10,264		10,612			10,264	10,612
Activity in loan portfolio
Balance at the beginning of the period						2,352,932	2,027,426	1,412,440
Acquisitions/originations/additional funding						1,002,908	661,598	817,104
Capitalized interest						518	503	0
Basis of loans sold						0	(26,824)	(12,678)
Loan maturities/principal repayments						(864,549)	(293,264)	(304,878)
Discount accretion/premium amortization						13,694	9,618	5,028
Changes in fair value						0	0	0
Foreign currency translation gain (loss), net						603	(2,895)	(711)
Credit loss provision, net						(10,446)	(6,848)	(12,580)
Loan foreclosure, equity control and conversion to equity interest						0	(16,382)	0
Transfer to/from other asset/liability classifications or between segments						0	0	123,701
Balance at the end of the period	2,495,660		2,352,932			2,495,660	2,352,932	2,027,426
Carrying Value	2,505,924		2,363,544			2,505,924	2,363,544
Infrastructure Portfolio Segment | Funded commitments
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						10,612	20,670	7,833
Credit loss (reversal) provision, net						10,446	6,848	12,580
Charge-offs						(10,794)	(16,906)	0
Transfers								257
Credit loss allowance at the end of the period	10,264		10,612			10,264	10,612	20,670
Charge-offs						10,794	16,906	0
Activity in loan portfolio
Credit loss provision, net						(10,446)	(6,848)	(12,580)
Infrastructure Portfolio Segment | Unfunded Loan Commitment, Loans Held-For-Investment
Activity in allowance for loan losses
Credit loss allowance at beginning of the period						72	145	812
Credit loss (reversal) provision, net						492	(73)	(667)
Credit loss allowance at the end of the period	564		72			564	72	145
Unfunded commitments	65,546					65,546
Activity in loan portfolio
Credit loss provision, net						(492)	73	667
Residential Portfolio Segment | 90 days or greater past due | Non-Credit Deterioration
Activity in loan portfolio
Carrying Value	67,600					67,600
Residential Portfolio Segment | Residential Loans
Activity in loan portfolio
Loan foreclosure, equity control and conversion to equity interest						(900)
Residential Portfolio Segment | First mortgage loan participation | New York
Activity in loan portfolio
Carrying Value									$ 29,000
Residential Portfolio Segment | Total loans held-for-investment
Activity in allowance for loan losses
Credit loss (reversal) provision, net						0	0	0
Activity in loan portfolio
Balance at the beginning of the period						0	59,225	90,684
Acquisitions/originations/additional funding						0	0	0
Capitalized interest						0	1,639	4,308
Basis of loans sold						0	0	0
Loan maturities/principal repayments						0	(7,623)	(31,251)
Discount accretion/premium amortization						0	0	0
Changes in fair value						0	(3,169)	1,186
Foreign currency translation gain (loss), net						0	0	0
Credit loss provision, net						0	0	0
Loan foreclosure, equity control and conversion to equity interest						0	0	0
Transfer to/from other asset/liability classifications or between segments						0	(50,072)	(5,702)
Balance at the end of the period	$ 0		$ 0			$ 0	$ 0	$ 59,225