Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic
Net income applicable to common stock	$ 15,535	$ 6,637	$ 43,985	$ 22,227
Average common shares outstanding (shares)	31,526,423	27,234,927	31,486,767	25,889,139
Net income per common share - basic (usd per share)	$ 0.49	$ 0.24	$ 1.40	$ 0.86
Diluted
Net income applicable to common stock	$ 15,535	$ 6,637	$ 43,985	$ 22,227
Average common shares outstanding (shares)	31,526,423	27,234,927	31,486,767	25,889,139
Effect of dilutive stock-based compensation (shares)	192,106	212,455	207,834	164,034
Average common shares outstanding - diluted (shares)	31,718,529	27,447,382	31,694,601	26,053,173
Net income per common share - diluted (usd per share)	$ 0.49	$ 0.24	$ 1.39	$ 0.85