Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2022 USD ($) director loan
Commitments And Contingencies [Line Items]
Number of members of board of directors | director	9
Number of directors eligible for annual compensation | director	6
Six Independent Board of Directors
Commitments And Contingencies [Line Items]
Annual cash compensation	$ 210,000
Annual cash compensation paid in cash	95,000
Annual cash compensation paid in the form of deferred stock units	115,000
Chairperson of Audit Committee
Commitments And Contingencies [Line Items]
Annual cash compensation	20,000
Compensation and Corporate Governance Committees
Commitments And Contingencies [Line Items]
Annual cash compensation	10,000
Compensation and Corporate Governance Committees | Amendment One
Commitments And Contingencies [Line Items]
Annual cash compensation	15,000
Audit Committee Members
Commitments And Contingencies [Line Items]
Annual cash compensation	10,000
Investment risk management committee
Commitments And Contingencies [Line Items]
Annual cash compensation	7,500
Total loans receivable
Commitments And Contingencies [Line Items]
Unfunded loan commitments	$ 4,500,000,000
Number of loans receivable | loan	126
Aggregate unfunded loan commitments	$ 2,500,000,000
Net unfunded commitments	$ 2,000,000,000.0
Weighted-average future funding period (in years)	3 years 6 months