Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator [Abstract]
Net income	$ 10,924	$ 12,653	$ 33,259	$ 36,415
Basic earnings per share [Abstract]
Weighted average shares (in shares)	17,326,000	17,154,000	17,317,000	17,123,000
Diluted earnings per share [Abstract]
Effect of dilutive stock options and restricted stock grants (in shares)	76,000	103,000	78,000	89,000
Adjusted weighted average shares (in shares)	17,402,000	17,257,000	17,395,000	17,212,000
Earnings per share [Abstract]
Basic earnings per share (in dollars per share)	$ 0.63	$ 0.74	$ 1.92	$ 2.13
Diluted earnings per share (in dollars per share)	$ 0.63	$ 0.73	$ 1.91	$ 2.12
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options excluded from diluted calculations (in shares)	63,270	0	0	97,071
Weighted average price for anti dilutive securities (in dollars per share)	$ 35.41	$ 0	$ 0	$ 35.41