Stockholders' Equity - Computation of basic and diluted earnings (loss) per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Weighted average Common Shares outstanding
Weighted average Common Shares outstanding	116,470,836	102,634,273
Nonvested shares	(1,795,752)	(1,202,185)
Weighted average Common Shares—Basic	114,675,084	101,432,088
Dilutive effect of restricted stock	725,346	601,509
Dilutive effect of employee stock purchase plan	106,572	131,221
Weighted average Common Shares outstanding—Diluted	115,507,002	102,164,818
Net Income
Income from continuing operations	$ 31,858	$ 9,163
Discontinued operations	(13)	(7)
NET INCOME	$ 31,845	$ 9,156
Basic Earnings (Loss) Per Common Share
Income from continuing operations (in dollars per share)	$ 0.28	$ 0.09
Discontinued operations (in dollars per share)
Net income (in dollars per share)	0.28	0.09
Diluted Earnings (Loss) Per Common Share
Income from continuing operations (in dollars per share)	0.28	0.09
Discontinued operations (in dollars per share)	0.00	0.00
Net income (in dollars per share)	$ 0.28	$ 0.09