Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Detail) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Valuation and Qualifying Accounts Disclosure [Line Items] | |||
| Balance, beginning of year | $ 95 | $ 95 | $ 373 |
| Additions charged to operations | 18 | 0 | |
| Deletions from Reserve | 0 | 278 | |
| Balance, end of year | $ 113 | $ 95 | $ 95 |