Loans - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	$ 21,397,743	$ 21,285,446
Allowance for credit losses	134,430	$ 99,413
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	16,213,072
Allowance for credit losses	118,479
Infrastructure Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	2,373,782
Allowance for credit losses	15,951
Credit deteriorated | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	4,925
Allowance for credit losses	4,925
Credit deteriorated | Infrastructure Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	12,907
Allowance for credit losses	6,724
Credit deteriorated | Senior Loans | Infrastructure Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual status	4,900
Credit deteriorated | Infrastructure Loans | Infrastructure Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual status	12,900
Allowance for credit losses	6,700
90 days or greater past due | Non-Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	280,400
90 days or greater past due | Non-Credit Deterioration | Residential Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	35,400
90 days or greater past due | Non-Credit Deterioration | Mortgage Loan | Brooklyn, New York | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual status	156,400
90 days or greater past due | Non-Credit Deterioration | Mortgage Loan | Chicago, Illinois | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	41,600
90 days or greater past due | Non-Credit Deterioration | Leasehold Mortgage Loan | California | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual status	37,800
90 days or greater past due | Non-Credit Deterioration | Senior Loans | New York | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	9,200
Not 90 days or greater past due | Non-Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Past due loan converted to equity interests	7,300
Not 90 days or greater past due | Non-Credit Deterioration | Mortgage Loan | Washington, DC | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	120,800
Not 90 days or greater past due | Non-Credit Deterioration | Senior Loans | New Jersey | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Carrying Value	$ 216,600