Acquisitions - Pro Forma Consolidated Results (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Revenues	$ 120,016	$ 115,210	$ 109,875	$ 103,948	$ 102,231	$ 95,907	$ 100,532	$ 95,618	$ 449,049	$ 394,288	$ 359,449
Sales, Pro Forma									454,333	438,981	396,767
Net income									16,570	19,710	23,044
Net income, Pro Forma									$ 17,112	$ 25,075	$ 22,033
EARNINGS PER COMMON SHARE:
Earnings per common share: basic (in dollars per share)	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.02	$ 0.17	$ 0.14	$ 0.14	$ 0.39	$ 0.47	$ 0.59
Earnings per common share: basic, Pro Forma (in dollars per share)									$ 0.40	$ 0	$ 0.56
Earnings per common share: diluted (in dollars per share)	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.01	$ 0.17	$ 0.14	$ 0.14	$ 0.39	$ 0.46	$ 0.58
Earnings per common share: diluted, Pro Forma (in dollars per share)									$ 0.40	$ 0	$ 0.55