Loans Held for Investment and the Allowance for Credit Losses - Summary of Aging Analysis for Loans Held for Investment Portfolio by Class of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	$ 5,115,788	$ 4,909,202
Current
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	5,092,788	4,886,202
Days: 90 or More
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	23,000	23,000
Total Loans Past Due
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	23,000	23,000
Senior Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	5,080,797	4,874,242
Senior Loans | Current
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	5,057,797	4,851,242
Senior Loans | Days: 90 or More
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	23,000	23,000
Senior Loans | Total Loans Past Due
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	23,000	23,000
Subordinated and Mezzanine Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	34,991	34,960
Subordinated and Mezzanine Loans | Current
Accounts Notes And Loans Receivable [Line Items]
Total loans past due	$ 34,991	$ 34,960