Stock Plans (Stock-based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of stock-based compensation expense
Stock-based compensation expense	$ 1,035	$ 1,011	$ 1,166	$ 755	$ 1,358	$ 719	$ 946	$ 957	$ 3,967	$ 3,980	$ 3,088
Total stock-based compensation expense									3,967	3,980	3,088
Cost of revenue [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									740	1,079	701
Selling, general and administrative [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									2,362	2,140	1,835
Research and development [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									865	761	552
Restricted Stock Units [Member]
Schedule of stock-based compensation expense
Stock-based compensation expense									255
Total stock-based compensation expense									867	592	421
Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member]
Schedule of stock-based compensation expense
Stock-based compensation expense									137
Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Three [Member]
Schedule of stock-based compensation expense
Stock-based compensation expense									28
Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Two [Member]
Schedule of stock-based compensation expense
Stock-based compensation expense									90
Employee Stock Option [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									52	827	978
Restricted Stock Awards [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									2,536	2,491	1,427
Employee Stock Purchase Plan [Member]
Schedule of stock-based compensation expense
Total stock-based compensation expense									$ 512	$ 70	$ 262