Debt and Preferred Equity Investments - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($) investment	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) investment segment	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) segment investment	Dec. 31, 2019 USD ($)
Preferred equity investment
Number of investments, nonperforming | investment	1		1		1
Carrying Value	$ 1,072,711,000		$ 1,072,711,000		$ 1,076,542,000
Recorded investment, nonaccrual status	27,700,000		$ 27,700,000		$ 27,700,000
Number of portfolio segments of financial receivables (segment) | segment			1		1
Additional amount of financing receivables included in other assets	66,400,000		$ 66,400,000		$ 66,200,000
Current period provision for loan loss	0	$ 3,400,000	0	$ 6,300,000	20,693,000
Allowance for loan and lease losses, real estate	13,213,000		13,213,000		13,213,000	$ 1,750,000
3 - High Risk Assets - Loss more likely than not
Preferred equity investment
Recorded investment, nonaccrual status	2,500,000		2,500,000
Financing Receivables, Equal to Greater than 90 Days Past Due
Preferred equity investment
Recorded investment, past due	0		0		0
Cumulative Effect, Period of Adoption, Adjustment
Preferred equity investment
Allowance for loan and lease losses, real estate					0	$ 27,803,000
Total floating rate
Preferred equity investment
Carrying Value	314,934,000		314,934,000		352,460,000
Total floating rate | Mortgage/Mezzanine Loan Due March 2020
Preferred equity investment
Carrying Value	$ 6,800,000		$ 6,800,000		$ 6,800,000