Revenue Recognition (Contract Balances) (Details) - USD ($) $ in Thousands |
6 Months Ended | ||
|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Dec. 31, 2017 |
|
| Revenue Recognition | |||
| Accounts receivable, net | $ 29,806 | $ 29,925 | |
| Allowance for Doubtful Accounts Receivable [Roll Forward] | |||
| Balance at the beginning of the period | 1,147 | ||
| Provision | 286 | $ 264 | |
| Write-offs | (104) | ||
| Balance at the end of the period | $ 1,329 | ||
| Payment term, general requirement for payment | 30 days | ||
| Balance at the beginning of the period | $ 7,682 | ||
| Deferred revenue | 4,266 | ||
| Recognition of deferred revenue | (3,871) | ||
| Balance at the end of the period | 8,077 | ||
| Contracted not recognized revenue | $ 9,500 | ||