Deferred compensation--Variables and Assumptions Used to Value Restricted Stock Awards (Detail) - 2010 Equity Incentive Plan - Predecessor - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Mar. 21, 2017 |
Dec. 31, 2016 |
|
| Performance Vested | Restricted Stock | ||||
| Stock-Based Compensation [Line Items] | ||||
| Risk free interest rate, minimum | 0.71% | 0.25% | ||
| Risk free interest rate, maximum | 1.44% | 1.48% | ||
| Expected volatility, minimum | 71.00% | 52.00% | ||
| Expected volatility, maximum | 81.00% | 56.00% | ||
| Expected life | 3 years | 4 years | ||
| Expected dividends | $ 0 | $ 0 | ||
| Service Vesting Conditions | Common Class A | Restricted Stock | ||||
| Stock-Based Compensation [Line Items] | ||||
| Discount for lack of marketability | 25.00% | 20.00% | ||
| Fair value per share of awards | $ 0 | $ 0.00 | ||
| Service Vesting Conditions | Common Class A | Time And Performance Awards | ||||
| Stock-Based Compensation [Line Items] | ||||
| Fair value per share of awards | $ 0.00 | |||