Summary of Secured Credit Facilities Secured by Commercial Mortgage Loans, CRE Debt Securities and Counterparty Concentration Risks (Parenthetical) (Details) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	May 31, 2020	Dec. 31, 2019
Repurchase Agreement Counterparty [Line Items]
Accrued Interest Payable	[1]	$ 2,661,000	$ 2,630,000
Commercial Mortgage Loans
Repurchase Agreement Counterparty [Line Items]
Interest receivable		6,200,000				$ 10,400,000
Premium, discount and origination fees		6,100,000	11,800,000
Accrued Interest Payable		900,000				1,000,000.0
Unamortized deferred financing fees		$ 4,400,000				$ 8,300,000
Commercial Mortgage Loans | Goldman Sachs
Repurchase Agreement Counterparty [Line Items]
Maximum commitment amount				$ 250,000,000.0	$ 750,000,000.0
Loan financings, increments in commitment amount				50,000,000.0
Commercial Mortgage Loans | Goldman Sachs | Maximum
Repurchase Agreement Counterparty [Line Items]
Loan financings. commitment incremental facility limit				$ 500,000,000.0
Commercial Mortgage Loans | Bank of America
Repurchase Agreement Counterparty [Line Items]
Maximum commitment amount			200,000,000.0		$ 500,000,000.0
Loan financings, increments in commitment amount			50,000,000.0
Commercial Mortgage Loans | Bank of America | Maximum
Repurchase Agreement Counterparty [Line Items]
Loan financings. commitment incremental facility limit			$ 500,000,000.0

[1] The Company’s consolidated Total Assets and Total Liabilities as of September 30, 2021 include assets and liabilities of variable interest entities (“VIEs”) of $3.5 billion and $2.8 billion, respectively. The Company’s consolidated Total Assets and Total Liabilities as of December 31, 2020 include assets and liabilities of VIEs of $2.3 billion and $1.8 billion, respectively. These assets can be used only to satisfy obligations of the VIEs, and creditors of the VIEs have recourse only to these assets, and not to TPG RE Finance Trust, Inc. See Note 6 to the Consolidated Financial Statements for details