Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Basic
Net income applicable to common stock	$ 14,853	$ 8,019	$ 28,450	$ 15,590
Average common shares outstanding (shares)	31,496,737	25,223,749	31,466,610	25,205,092
Net income per common share - basic (usd per share)	$ 0.47	$ 0.32	$ 0.90	$ 0.62
Diluted
Net income applicable to common stock	$ 14,853	$ 8,019	$ 28,450	$ 15,590
Average common shares outstanding (shares)	31,496,737	25,223,749	31,466,610	25,205,092
Effect of dilutive stock-based compensation (shares)	201,461	150,119	215,886	129,806
Average common shares outstanding - diluted (shares)	31,698,198	25,373,868	31,682,496	25,334,898
Net income per common share - diluted (usd per share)	$ 0.47	$ 0.32	$ 0.90	$ 0.62