Debt and Preferred Equity Investments - Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) segment loan	Dec. 31, 2018 USD ($) segment loan	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Preferred equity investment
Allowance for loan and lease losses	$ 1,750,000	$ 5,750,000	$ 0	$ 0
Number of investments marketed for sale | loan	1	2
Unpaid principal balance	$ 142,900,000	$ 159,900,000
Carrying value	$ 1,580,306,000	$ 2,099,393,000
Number of portfolio segments of financial receivables (segment) | segment	1	1
Additional amount of financing receivables included in other assets	$ 131,100,000	$ 124,500,000
Financing receivable, nonaccrual status	$ 28,400,000
Weighted average risk rating	1.2
Financing Receivables, Equal to Greater than 90 Days Past Due
Preferred equity investment
Financing receivable, past due	$ 0