Stock Plans (Stock Option Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Shares
Balance at beginning of period	1,183,659
Exercised	(145,703)
Cancelled	(114,200)
Balance at end of period	923,756
Vested and expected to vest	915,451
Exercisable	807,146	884,959	928,380
Weighted Average Exercise Price
Balance at beginning of period	$ 11.45
Exercised	$ 7.85
Cancelled	$ 14.34
Balance at end of period	$ 11.67
Vested and expected to vest	$ 11.64
Exercisable	$ 11.53	$ 11.14	$ 10.44
Additional Disclosures
Options, outstanding, weighted average remaining contractual term (in years)	4 years 7 months 13 days
Options, outstanding, aggregate intrinsic value	$ 261,981
Options, vested and expected to vest, weighted average remaining contractual term (in years)	4 years 7 months 6 days
Options, vested and expected to vest, aggregate intrinsic value	261,049
Options, exercisable, weighted average remaining contractual term (in years)	4 years 3 months 22 days
Options, exercisable, aggregate intrinsic value	$ 221,133