Loans - Risk Ratings by Class of Loan (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Investments in loans
Total Amortized Cost Basis	$ 20,107,790	$ 21,285,446
Credit Loss Allowance	271,320	99,413
Loans under fair value option
Investments in loans
Total Amortized Cost Basis	2,602,265	$ 2,784,594
Credit Loss Allowance	0
Commercial Portfolio Segment
Investments in loans
2023	420,646
2022	3,993,258
2021	7,282,056
2020	722,823
2019	1,527,576
Prior	1,275,442
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	15,221,801
Credit Loss Allowance	261,914
Commercial Portfolio Segment | LTV less than 60%
Investments in loans
2023	265,245
2022	1,937,607
2021	3,101,829
2020	188,077
2019	991,760
Prior	206,365
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	6,690,883
Credit Loss Allowance	24,768
Commercial Portfolio Segment | LTV 60% - 70%
Investments in loans
2023	85,019
2022	1,911,675
2021	3,526,879
2020	94,397
2019	102,782
Prior	386,971
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	6,107,723
Credit Loss Allowance	73,696
Commercial Portfolio Segment | LTV > 70%
Investments in loans
2023	40,008
2022	102,433
2021	653,348
2020	440,349
2019	433,034
Prior	637,766
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	2,306,938
Credit Loss Allowance	158,525
Commercial Portfolio Segment | Credit deteriorated
Investments in loans
2023	0
2022	0
2021	0
2020	0
2019	0
Prior	29,065
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	29,065
Credit Loss Allowance	4,925
Commercial Portfolio Segment | Defeased and other
Investments in loans
2023	30,374
2022	41,543
2021	0
2020	0
2019	0
Prior	15,275
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	87,192
Credit Loss Allowance	0
Infrastructure Portfolio Segment
Investments in loans
2023	554,050
2022	123,212
2021	453,913
2020	75,616
2019	466,991
Prior	602,137
Revolving Loans Amortized Cost Total	7,805
Total Amortized Cost Basis	2,283,724
Credit Loss Allowance	9,406
Infrastructure Portfolio Segment | Credit deteriorated
Investments in loans
2023	0
2022	0
2021	0
2020	0
2019	0
Prior	1,801
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	1,801
Credit Loss Allowance	0
Infrastructure Portfolio Segment | Defeased and other
Investments in loans
2023	48,744
2022	0
2021	0
2020	0
2019	0
Prior	0
Revolving Loans Amortized Cost Total	0
Total Amortized Cost Basis	48,744
Credit Loss Allowance	201
Infrastructure Portfolio Segment | Power
Investments in loans
2023	288,797
2022	0
2021	107,644
2020	75,616
2019	278,309
Prior	465,377
Revolving Loans Amortized Cost Total	5,757
Total Amortized Cost Basis	1,221,500
Credit Loss Allowance	3,722
Infrastructure Portfolio Segment | Oil and gas
Investments in loans
2023	216,509
2022	123,212
2021	346,269
2020	0
2019	188,682
Prior	134,959
Revolving Loans Amortized Cost Total	2,048
Total Amortized Cost Basis	1,011,679
Credit Loss Allowance	$ 5,483