Debt and Preferred Equity Investments - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Aggregate weighted average current yield (as a percent)	6.26%
Debt Investments Held [Abstract]
Carrying Value	$ 1,153,363	$ 1,580,306
Mezzanine Loan With Initial Maturity Date Of January 2021
Debt Investments Held [Abstract]
Amount participated out	66,600
Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Amount participated out	12,000
Mezzanine Loan Due March 2022
Debt Investments Held [Abstract]
Amount participated out	400
Debt Investments in Mortgage Loans
Debt Investments Held [Abstract]
Future Funding Obligations	165,023
Senior Financing	4,930,044
Allowance for loan loss	(19,010)	0
Carrying Value	896,798	1,341,070
Total fixed rate
Debt Investments Held [Abstract]
Future Funding Obligations	10,000
Senior Financing	2,781,827
Carrying Value	476,724	499,410
Total fixed rate | Mortgage And Mezzanine Loan With An Initial Maturity Date Of October 2020
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	63,750
Carrying Value	56,242	55,573
Total fixed rate | Mezzanine Loan With Initial Maturity Date Of January 2021
Debt Investments Held [Abstract]
Future Funding Obligations	10,000
Senior Financing	67,000
Carrying Value	32,805	0
Total fixed rate | Mezzanine Loan, September 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	15,000
Carrying Value	3,500	3,500
Total fixed rate | Mezzanine Loan With An Initial Maturity Of August 2022
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	280,000
Carrying Value	40,458	38,734
Total fixed rate | Mezzanine Loan With Maturity June 2023
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	348,327
Carrying Value	225,204	215,737
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	115,000
Carrying Value	13,265	12,950
Total fixed rate | Mezzanine Loan, with an Initial Maturity Date of January 2025
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	95,000
Carrying Value	30,000	30,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2027
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,712,750
Carrying Value	55,250	55,250
Total fixed rate | Mezzanine Loan With Initial Maturity Date Of December 2029
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	85,000
Carrying Value	20,000	20,000
Total fixed rate | Mezzanine Loan Repaid In 2020, 1
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	24,952
Total fixed rate | Mezzanine Loan Repaid In 2020, 2
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	30,000
Total fixed rate | Mezzanine Loan Repaid In 2020, 3
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	12,714
Total floating rate
Debt Investments Held [Abstract]
Future Funding Obligations	155,023
Senior Financing	2,148,217
Carrying Value	439,084	841,660
Total floating rate | Mezzanine Loan Repaid In 2020, 1
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	51,387
Total floating rate | Junior Mortgage Loan With An Initial Maturity April 2020
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	40,000
Carrying Value	20,000	20,000
Total floating rate | Mezzanine Loan With An Initial Maturity Due April 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	275,000
Carrying Value	49,919	49,809
Total floating rate | Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity of July 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	60,000
Carrying Value	15,724	15,698
Total floating rate | Mezzanine Loan With An Initial Maturity Due July 2021
Debt Investments Held [Abstract]
Future Funding Obligations	7,933
Senior Financing	169,540
Carrying Value	46,613	41,395
Total floating rate | Mezzanine Loan Due July 2021, 2
Debt Investments Held [Abstract]
Future Funding Obligations	5,329
Senior Financing	54,204
Carrying Value	23,753	15,743
Total floating rate | Mezzanine Loan Due March 2022
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,115,000
Carrying Value	126,486	222,775
Total floating rate | Mortgage/Mezzanine Loan Due May 2022
Debt Investments Held [Abstract]
Future Funding Obligations	7,425
Senior Financing	0
Carrying Value	60,116	0
Total floating rate | Mezzanine Loan Due December 2022
Debt Investments Held [Abstract]
Future Funding Obligations	44,000
Senior Financing	0
Carrying Value	13,987	13,918
Total floating rate | Mortgage Loan Due February 2023
Debt Investments Held [Abstract]
Future Funding Obligations	35,303
Senior Financing	375,241
Carrying Value	63,899	0
Total floating rate | Mezzanine Loan Due May 2023
Debt Investments Held [Abstract]
Future Funding Obligations	55,033
Senior Financing	59,232
Carrying Value	18,587	69,839
Total floating rate | Mortgage/Mezzanine Loan Repaid In 2020, 1
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	35,386
Total floating rate | Mortgage Loan Repaid In 2020, 1
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	19,971
Total floating rate | Mortgage Loan Repaid In 2020, 2
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	106,473
Total floating rate | Mortgage/Mezzanine Loan Repaid In 2020, 2
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	96,570
Total floating rate | Mortgage/Mezzanine Loan Repaid In 2020, 3
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0	$ 82,696