Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator [Abstract]
Net income	$ 11,277	$ 11,602
Basic earnings per share [Abstract]
Weighted average shares (in shares)	17,615,000	17,513,000
Diluted earnings per share [Abstract]
Effect of dilutive stock options and restricted stock grants (in shares)	23,000	20,000
Adjusted weighted average shares (in shares)	17,638,000	17,533,000
Earnings per share [Abstract]
Basic earnings per share (in dollars per share)	$ 0.64	$ 0.66
Diluted earnings per share (in dollars per share)	$ 0.64	$ 0.66
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options excluded from diluted calculations (in shares)	0	57,953
Weighted average price for anti dilutive securities (in dollars per share)		$ 35.41