Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock	$ 6,376	$ 6,362	$ 19,128	$ 19,086
Undistributed earnings allocated to common stock	6,699	4,125	17,901	21,040
Net earnings allocated to common shareholders	$ 13,075	$ 10,487	$ 37,029	$ 40,126
Average shares outstanding (in shares)	14,899,000	15,178,000	14,902,000	15,111,000
Effect of dilutive securities:
Warrant outstanding	0	0	0	37,000
Employee stock awards	11,000	20,000	11,000	21,000
Shares for diluted earnings per share (in shares)	14,910,000	15,198,000	14,913,000	15,169,000
Basic earnings per common share (in dollars per share)	$ 0.88	$ 0.69	$ 2.48	$ 2.66
Diluted earnings per share (in dollars per share)	$ 0.88	$ 0.69	$ 2.48	$ 2.65
Options to purchase shares of common stock, anti-dilutive (in shares)	3,000	0	5,000	0