Variable Interest Entities and Securitized Debt Obligations - Narrative (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 16, 2023 USD ($) loan	Jun. 30, 2023 USD ($) loan	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) loan	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Variable Interest Entity [Line Items]
Securitized debt obligations		$ 999,781		$ 999,781		$ 1,138,749
Number of loans | loan		4		4
Gain (loss) on extinguishment of debt		$ 0	$ (13,032)	$ 238	$ (18,823)
GPMT 2019-FL2 CRE CLO
Variable Interest Entity [Line Items]
Gain (loss) on extinguishment of debt	$ 300
Financing provided
Variable Interest Entity [Line Items]
Securitized debt obligations		999,781		999,781		1,138,749
Principal Balance		1,002,525		1,002,525		1,141,740
Financing provided | GPMT 2019-FL2 CRE CLO
Variable Interest Entity [Line Items]
Securitized debt obligations	$ 98,100	0		0		99,608
Principal Balance		0		0		99,300
Collateral assets
Variable Interest Entity [Line Items]
Securitized debt obligations		1,223,998		1,223,998		1,541,540
Principal Balance		1,259,209		1,259,209		1,569,622
Collateral assets | GPMT 2019-FL2 CRE CLO
Variable Interest Entity [Line Items]
Securitized debt obligations		0		0		264,907
Number of loans | loan	11
Principal Balance	$ 269,300	$ 0		$ 0		$ 270,498