Fair Value Measurements - Summary of Activity for Assets Measured at Fair Value Using Significant Unobservable Inputs (Detail) $ in Thousands |
12 Months Ended |
|---|---|
|
Dec. 31, 2016
USD ($)
| |
| Fair Value Disclosures [Abstract] | |
| Balance at December 31, 2015 | $ 2,052 |
| Total net realized gains included in earnings | 0 |
| Total net unrealized loss included in other comprehensive income | (6) |
| Net transfers in and/out of Level 3 | 0 |
| Balance at December 31, 2016 | 2,046 |
| Amount of total losses for the period included in net loss attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2016 | $ 0 |