Nature of operations and summary of significant accounting policies (Asset Impairment) (Detail) - Predecessor $ in Thousands |
1 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
|
Oct. 31, 2016
USD ($)
Rig
|
Dec. 31, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
Rig
|
Dec. 31, 2014
USD ($)
|
|
| Long Lived Assets Held For Sale [Line Items] | ||||
| Loss on impairment of other assets | $ 1,393 | $ 16,207 | $ 0 | |
| Number of drilling rigs to be sold | Rig | 4 | |||
| Number of drilling rigs to be sold | Rig | 4 | |||
| Sale price of drilling rigs | $ 2,000 | |||
| Sale of property closing period | 2017-01 | |||
| Upstream Equipment | ||||
| Long Lived Assets Held For Sale [Line Items] | ||||
| Loss on impairment of other assets | $ 6,015 | |||