Stock-based Compensation Plans and Awards - Employee Stock Purchase Plan - (Details)
$ in Thousands |
1 Months Ended |
3 Months Ended |
9 Months Ended |
May 31, 2011 |
Sep. 30, 2016
USD ($)
shares
|
Sep. 30, 2015
USD ($)
|
Sep. 30, 2016
USD ($)
item
shares
|
Sep. 30, 2015
USD ($)
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
|
|
|
|
| Stock-based compensation expense | $ |
|
$ 1,680
|
$ 1,559
|
$ 6,118
|
$ 5,683
|
| Employee Stock Purchase Plan |
|
|
|
|
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
|
|
|
|
| Share-based compensation arrangement by share-based payment award, discount from market price, lower of purchase and offer date |
15.00%
|
|
|
|
|
| Participants maximum payroll deductions percentage |
15.00%
|
|
|
|
|
| Duration of each offering period |
|
|
|
12 months
|
|
| Number of purchase periods in each offering period | item |
|
|
|
2
|
|
| Duration of each purchase period |
|
|
|
6 months
|
|
| Maximum number of common stock shares may be purchased by each participant |
|
|
|
500
|
|
| Fair value assumptions, expected volatility, minimum |
|
|
|
41.00%
|
|
| Fair value assumptions, expected volatility, maximum |
|
|
|
48.00%
|
|
| Number of common stock shares remaining authorized for issuance |
|
1,700,000
|
|
1,700,000
|
|