Net Income Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Common stock excluded from calculation of EPS	385	334	373	321
Computation of basic and diluted net income per common share
Net income	$ 7,193	$ 8,399	$ 14,823	$ 15,962
Basic (in dollars per share)	$ 0.15	$ 0.18	$ 0.32	$ 0.35
Diluted (in dollars per share)	$ 0.15	$ 0.18	$ 0.31	$ 0.33
Weighted average common shares outstanding - basic	46,479	46,039	46,416	45,927
Plus dilutive effect of potential common shares	1,357	1,798	1,460	1,832
Weighted average common shares outstanding - diluted	47,836	47,837	47,876	47,759