Segment Information - Additional Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment information
Number of reportable segments (segment) | segment									2
Total revenues	$ 308,082	$ 313,634	$ 313,024	$ 304,255	$ 317,036	$ 307,545	$ 301,116	$ 301,695	$ 1,238,995	$ 1,227,392	$ 1,511,473
Net Income									291,487	270,856	101,069
Total assets	12,766,320				12,751,358				12,766,320	12,751,358
Marketing, general and administrative									100,875	92,631	100,498
Operating Segments | Real Estate Segment
Segment information
Total revenues									1,043,405	1,025,900	1,317,602
Net Income									158,972	129,253	(69,294)
Total assets	11,063,155				10,481,594				11,063,155	10,481,594
Operating Segments | Debt and Preferred Equity Segment
Segment information
Total revenues									195,590	201,492	193,871
Net Income									132,515	141,603	$ 170,363
Total assets	$ 1,703,165				$ 2,269,764				$ 1,703,165	$ 2,269,764