EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 20,244	$ 18,482	$ 39,293	$ 33,848
Allocation to participating securities: Unvested LTIP Units	(97)	(101)	(196)	(184)
Numerator for basic and diluted net income attributable to common stock holders	$ 20,147	$ 18,381	$ 39,097	$ 33,664
Weighted average shares of common stock outstanding - basic (in shares)	155,898	147,722	154,203	147,479
Effect of dilutive securities: Stock options (in shares)	54	5,083	607	4,687
Weighted average shares of common stock and common stock equivalents outstanding - diluted (in shares)	155,952	152,805	154,810	152,166
Basic EPS:
Net income attributable to common stockholders per share (usd per share)	$ 0.129	$ 0.124	$ 0.254	$ 0.228
Diluted EPS:
Net income attributable to common stockholders per share (usd per share)	$ 0.129	$ 0.120	$ 0.253	$ 0.221
Operating Partnership Units and Vested LTIP Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of weighted average diluted shares (in shares)	24,797	25,114	24,730	25,331
Vested LTIP Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of weighted average diluted shares (in shares)	313	807	536	811