CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income Available for Common Shareholders	Cumulative Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017	$ 2,755,422	$ 1,643	$ (4,834,491)	$ 4,542,307	$ 2,966,605	$ 79,358
Beginning balance (in shares) at Dec. 31, 2017		164,349,141
Increase (Decrease) in Shareholders' Equity
Net income	80,206				80,206
Equity interest in investee’s unrealized gains (losses)	(93)					(93)
Common share repurchases	(101)			(101)
Common share repurchases (in shares)		(3,394)
Distributions	(85,460)		(85,460)
Ending balance at Mar. 31, 2018	2,749,974	$ 1,643	(4,919,951)	4,542,206	3,126,367	(291)
Ending balance (in shares) at Mar. 31, 2018		164,345,747
Beginning balance at Dec. 31, 2018	2,597,431	$ 1,644	(5,181,323)	4,545,481	3,231,895	(266)
Beginning balance (in shares) at Dec. 31, 2018		164,441,709
Increase (Decrease) in Shareholders' Equity
Net income	225,787				225,787
Equity interest in investee’s unrealized gains (losses)	66					66
Common share grants	436			436
Distributions	(87,154)		(87,154)
Ending balance at Mar. 31, 2019	$ 2,736,566	$ 1,644	$ (5,268,477)	$ 4,545,917	$ 3,457,682	$ (200)
Ending balance (in shares) at Mar. 31, 2019		164,441,709