Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Basic
Net income available to common shareholders	$ 12,569	$ 11,510
Less: dividends and undistributed earnings allocated to unvested restricted stock awards	(117)	(34)
Net earnings allocated to common shareholders	12,452	11,476
Weighted average shares outstanding, including participating securities	14,781,394	14,427,114
Less: average participating securities	(136,846)	(52,849)
Weighted average shares outstanding - Basic	14,644,548	14,374,265
Diluted
Net earnings allocated to common shareholders	12,452	11,476
Dilutive effect of common stock options or restricted stock awards	$ 130,838	$ 62,492
Weighted average shares outstanding - Diluted	14,775,386	14,436,757
Basic EPS (in dollars per share)	$ 0.85	$ 0.80
Diluted EPS (in dollars per share)	$ 0.84	$ 0.79