Stock-based Compensation - Employee Stock Purchase Plan (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
May 09, 2018 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Aggregate number of shares of common stock issued or transferred under the incentive stock awards plan (in shares) | 1,441,744 | ||
| Options outstanding, weighted average exercise price (in dollars per share) | $ 30.42 | $ 25.56 | |
| Employee Stock | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| ESPP purchase price of common stock, percent of market price, on first and last day of trading date | 85.00% | ||
| Fixed contribution rate | 10.00% | ||
| Maximum contribution amount | $ 25,000 | ||
| Compensation cost for ESPP | $ 200,000 | ||
| Number of shares issued under the ESPP | 25,239 | ||
| Aggregate number of shares of common stock issued or transferred under the incentive stock awards plan (in shares) | 174,761 | ||
| Options outstanding, weighted average exercise price (in dollars per share) | $ 35.74 |