Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average Common Shares
Weighted average Common Shares outstanding									109,861,580	100,280,059	97,093,960
Non-vested shares									(1,289,478)	(1,108,707)	(1,814,734)
Weighted average Common Shares - Basic									108,572,102	99,171,352	95,279,226
Dilutive effect of non-vested shares									709,559	623,212	1,364,236
Dilutive effect of employee stock purchase plan									105,336	85,738	115,948
Weighted average Common Shares - Diluted									109,386,997	99,880,302	96,759,410
Net Income
Income (loss) from continuing operations	$ 52,580	$ 11,857	$ 12,157	$ 9,163	$ 19,354	$ 16,848	$ 17,586	$ 5,049	$ 85,756	$ 58,836	$ 33,979
Noncontrolling interests’ share in earnings	0	0	0	0	0	0	0	0			(313)
Income from continuing operations attributable to common stockholders									85,756	58,836	33,666
Income (loss) from discontinued operations	(143)	(23)	(12)	(7)	(696)	10,632	330	333	(185)	10,600	(1,779)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ 52,437	$ 11,834	$ 12,145	$ 9,156	$ 18,658	$ 27,480	$ 17,916	$ 5,382	$ 85,571	$ 69,436	$ 31,887
Basic Earnings (loss) Per Common Share
Income (loss) from continuing operations (in dollars per share)									$ 0.79	$ 0.59	$ 0.35
Income (loss) from discontinued operations (in dollars per share)									0.00	0.11	(0.02)
Net income attributable to common stockholders (in dollars per share)	$ 0.46	$ 0.10	$ 0.12	$ 0.09	$ 0.19	$ 0.28	$ 0.18	$ 0.05	0.79	0.70	0.33
Diluted Earnings (loss) Per Common Share
Income (loss) from continuing operations (in dollars per share)									0.78	0.59	0.35
Income (loss) from discontinued operations (in dollars per share)									0.00	0.11	(0.02)
Net income attributable to common stockholders (in dollars per share)	$ 0.45	$ 0.10	$ 0.12	$ 0.09	$ 0.19	$ 0.27	$ 0.18	$ 0.05	$ 0.78	$ 0.70	$ 0.33