Valuation And Qualifying Accounts (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Valuation and Qualifying Accounts Disclosure [Line Items] | |||
| Balance at beginning of period | $ 25 | $ 25 | |
| Additions | 0 | $ 25 | |
| Deduction | $ 25 | 0 | |
| Balance at end of period | $ 25 | $ 25 | |