Condensed Consolidated Statements of Equity (Unaudited) Statement - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Cumulative Net Income Attributable to Common Stockholders [Member]	Cumulative Dividends [Member]
Beginning balance at Dec. 31, 2016	$ 1,653,414	$ 1,164	$ 2,917,914	$ (1,401)	$ 995,256	$ (2,259,519)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock	815		815
Common stock redemptions	(503)		(503)
Stock-based compensation	2,614	1	2,613
Net Income	31,845				31,845
Reclassification of loss on forward starting interest rate swaps	43			43
Dividends to common stockholders ($0.30 per share)	(34,937)					(34,937)
Ending balance at Mar. 31, 2017	$ 1,653,291	$ 1,165	$ 2,920,839	$ (1,358)	$ 1,027,101	$ (2,294,456)