Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator [Abstract]
Net income	$ 11,566	$ 12,402	$ 23,168	$ 23,340
Basic earnings per share [Abstract]
Weighted average shares (in shares)	17,530,000	17,421,000	17,521,000	17,411,000
Diluted earnings per share [Abstract]
Effect of dilutive stock options and restricted stock grants (in shares)	12,000	44,000	17,000	47,000
Adjusted weighted average shares (in shares)	17,542,000	17,465,000	17,538,000	17,458,000
Earnings per share [Abstract]
Basic earnings per share (in dollars per share)	$ 0.66	$ 0.71	$ 1.32	$ 1.34
Diluted earnings per share (in dollars per share)	$ 0.66	$ 0.71	$ 1.32	$ 1.34
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options excluded from diluted calculations (in shares)	0	58,063	67,953	58,063
Weighted average price for anti dilutive securities (in dollars per share)	$ 35.31	$ 35.409	$ 35.31	$ 35.409