Stockholders' Equity and Stock-based Compensation Expense (Details) (USD $) | 3 Months Ended | 9 Months Ended |
Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Stock-based compensation expense | $748,000 | $809,000 | $2,370,000 | $2,334,000 |
Number of shares of common stock issued (in shares) | ' | ' | 556,674 | ' |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ' | ' | ' | ' |
Number of shares of common stock granted (in shares) | ' | ' | 1,230,000 | ' |
Unrecognized compensation expense, net of projected forfeitures | 5,100,000 | ' | 5,100,000 | ' |
Period for Recognition | ' | ' | '2 years 9 months 18 days | ' |
Stock Options [Member] | ' | ' | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ' | ' | ' | ' |
Number of shares of common stock granted (in shares) | ' | ' | 1,007,000 | ' |
Restricted Stock Units [Member] | ' | ' | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ' | ' | ' | ' |
Number of shares of common stock granted (in shares) | ' | ' | 189,000 | ' |
Performance Stock Units [Member] | ' | ' | ' | ' |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ' | ' | ' | ' |
Number of shares of common stock granted (in shares) | ' | ' | 34,000 | ' |
Original stock buyback program [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Increase in the authorized amount under the stock repurchase plan | ' | ' | 10,000,000 | ' |
Modified stock buyback program [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Amount authorized by the Board of Directors for stock repurchase program | ' | ' | 20,000,000 | ' |
Shares of common stock repurchased (in shares) | 796,919 | ' | ' | ' |
Value of common stock repurchased | 7,600,000 | ' | ' | ' |
Remaining amount available for the stock repurchase program | ' | ' | 12,400,000 | ' |
Cost of Revenue [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Stock-based compensation expense | 159,000 | 169,000 | 484,000 | 480,000 |
Sales and Marketing [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Stock-based compensation expense | 182,000 | 177,000 | 579,000 | 476,000 |
Research and Development [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Stock-based compensation expense | 103,000 | 126,000 | 293,000 | 419,000 |
General and Administrative [Member] | ' | ' | ' | ' |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs and Stock repurchase program [Line Items] | ' | ' | ' | ' |
Stock-based compensation expense | $304,000 | $337,000 | $1,014,000 | $959,000 |