Earnings Per 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
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock	$ 6,178	$ 5,751	$ 12,356	$ 11,502
Undistributed earnings allocated to common stock	6,448	7,139	13,931	9,303
Net Income (Loss) Available to Common Stockholders, Basic	$ 12,626	$ 12,890	$ 26,287	$ 20,805
Average shares outstanding (in shares)	15,556,000	15,582,000	15,583,000	15,521,000
Effect of dilutive securities:
Warrant outstanding (in shares)	62,000	62,000	62,000	59,000
Employee stock awards (in shares)	88,000	108,000	93,000	107,000
Shares for diluted earnings per share (in shares)	15,706,000	15,752,000	15,738,000	15,687,000
Basic earnings per share (in dollars per share)	$ 0.81	$ 0.83	$ 1.69	$ 1.34
Diluted earnings per share (in dollars per share)	$ 0.80	$ 0.82	$ 1.67	$ 1.33
Options to purchase shares of common stock, anti-dilutive (in shares)	0	57,500
Common stock exercise price, lower limit (in dollars per share)		$ 39.34
Common stock exercise price, upper limit (in dollars per share)		$ 40.88