Stockholders' Equity - Computation of basic and diluted earnings (loss) per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Weighted average Common Shares outstanding
Weighted average Common Shares outstanding	125,908,335	125,167,128
Nonvested shares	(1,778,700)	(1,909,777)
Weighted average Common Shares—Basic	124,129,635	123,257,351
Dilutive effect of employee stock purchase plan	102,132	90,330
Weighted average Common Shares outstanding—Diluted	124,231,767	123,347,681
Net Income	$ 4,891	$ 9,180
Dividends paid on nonvested share-based awards	(536)	(579)
Net income applicable to common stockholders	$ 4,355	$ 8,601
Basic earnings per common share (in dollars per share)	$ 0.04	$ 0.07
Diluted earnings per common share (in dollars per share)	$ 0.04	$ 0.07