Net Income Per Common Share - (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Basic
Net income applicable to common stock	$ 22,900	$ 15,394	$ 44,116	$ 30,634
Average common shares outstanding (shares)	42,066,168	31,626,059	41,200,133	31,601,304
Net income per common share - basic (usd per share)	$ 0.54	$ 0.49	$ 1.07	$ 0.97
Diluted
Net income applicable to common stock	$ 22,900	$ 15,394	$ 44,116	$ 30,634
Average common shares outstanding (shares)	42,066,168	31,626,059	41,200,133	31,601,304
Effect of dilutive stock-based compensation (shares)	237,458	239,113	235,830	232,953
Average common shares outstanding - diluted (shares)	42,303,626	31,865,172	41,435,963	31,834,257
Net income per common share - diluted (usd per share)	$ 0.54	$ 0.48	$ 1.06	$ 0.96