Investments (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Sep. 08, 2017
Schedule of Equity Method Investments
Equity income (loss)	$ (4,100,000)	$ 4,800,000	$ (4,116,000)	$ 4,750,000
Distributions received			0		$ 8,600,000
Equity method investment	95,850,000		95,850,000		99,966,000
Unrealized (gains) loss on marketable securities	(10,000,000.0)	$ 3,900,000	(26,800)	$ 3,900,000
Other Assets
Schedule of Equity Method Investments
Equity method investment	95,900,000		95,900,000		100,000,000.0
Alternative investment	$ 67,300,000		$ 67,300,000		$ 94,100,000
CF Real Estate Finance Holdings, L.P.
Schedule of Equity Method Investments
Equity method investment ownership percentage (in percentage)	27.00%		27.00%
Equity method investment						$ 100,000,000.0