Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic
Net income available to common shareholders	$ 11,007	$ 8,826	$ 22,516	$ 16,640
Less : dividends and undistributed earnings allocated to unvested restricted stock awards	(112)	(33)	(147)	(67)
Net earnings allocated to common shareholders	10,895	8,793	22,369	16,573
Weighted average shares outstanding, including participating securities (in shares)	14,541,222	12,195,047	14,482,584	11,673,332
Less: average participating securities (in shares)	(113,384)	(48,425)	(78,190)	(48,607)
Weighted average shares outstanding - Basic (in shares)	14,427,838	12,146,622	14,404,394	11,624,725
Diluted
Net earnings allocated to common shareholders	10,895	8,793	22,369	16,573
Dilutive effect of common stock options or restricted stock awards	$ 69,021	$ 19,795	$ 67,542	$ 32,046
Weighted average shares outstanding - Diluted (in shares)	14,496,859	12,166,417	14,471,936	11,656,771
Basic EPS (in dollars per share)	$ 0.76	$ 0.72	$ 1.55	$ 1.43
Diluted EPS (in dollars per share)	$ 0.75	$ 0.72	$ 1.55	$ 1.42