Nature of operations and summary of significant accounting policies (Inventory Adjustments) (Detail) - Predecessor - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Inventory Adjustments | |||
| Inventory - lower of cost or market adjustment | $ 1,393 | $ 16,207 | $ 0 |
| Other Energy Equipment | |||
| Inventory Adjustments | |||
| Inventory - lower of cost or market adjustment | $ 1,393 | $ 10,192 | |