Net Income Per Common Share - (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Basic
Net income applicable to common stock	$ 21,216	$ 15,240
Average common shares outstanding (shares)	40,324,475	31,576,275
Net income per common share - basic (usd per share)	$ 0.53	$ 0.48
Diluted
Net income applicable to common stock	$ 21,216	$ 15,240
Average common shares outstanding (shares)	40,324,475	31,576,275
Effect of dilutive stock-based compensation (shares)	234,670	239,435
Average common shares outstanding - diluted (shares)	40,559,145	31,815,710
Net income per common share - diluted (usd per share)	$ 0.52	$ 0.48