Fair value measurements (Fair Value of Other Financial Instruments) (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
New Term Loan
Fair Value of Other Financial Instruments
New Credit Facility		$ 148,541
New Revolver
Fair Value of Other Financial Instruments
New Credit Facility		153,000
Significant Other Observable Inputs (Level 2) | Carrying Value | New Term Loan
Fair Value of Other Financial Instruments
New Credit Facility	[1]	149,192
Significant Other Observable Inputs (Level 2) | Carrying Value | New Revolver
Fair Value of Other Financial Instruments
New Credit Facility	[1]	153,000
Significant Other Observable Inputs (Level 2) | Estimated Fair Value | New Term Loan
Fair Value of Other Financial Instruments
New Credit Facility		149,192
Significant Other Observable Inputs (Level 2) | Estimated Fair Value | New Revolver
Fair Value of Other Financial Instruments
New Credit Facility		153,000
Significant Other Observable Inputs (Level 2) | 9.875% Senior Notes due 2020 | Carrying Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes	[1]		$ 298,000
Significant Other Observable Inputs (Level 2) | 9.875% Senior Notes due 2020 | Estimated Fair Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes			268,200
Significant Other Observable Inputs (Level 2) | 8.25% Senior Notes due 2021 | Carrying Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes	[1]		384,045
Significant Other Observable Inputs (Level 2) | 8.25% Senior Notes due 2021 | Estimated Fair Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes			344,680
Significant Other Observable Inputs (Level 2) | 7.625% Senior Notes due 2022 | Carrying Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes	[1]		525,910
Significant Other Observable Inputs (Level 2) | 7.625% Senior Notes due 2022 | Estimated Fair Value | Predecessor
Fair Value of Other Financial Instruments
Senior Notes			470,689
Significant Other Observable Inputs (Level 2) | Secured Debt | Carrying Value
Fair Value of Other Financial Instruments
Other secured debt	[1]	9,338
Significant Other Observable Inputs (Level 2) | Secured Debt | Carrying Value | Predecessor
Fair Value of Other Financial Instruments
Other secured debt	[1]		10,029
Significant Other Observable Inputs (Level 2) | Secured Debt | Estimated Fair Value
Fair Value of Other Financial Instruments
Other secured debt		$ 9,338
Significant Other Observable Inputs (Level 2) | Secured Debt | Estimated Fair Value | Predecessor
Fair Value of Other Financial Instruments
Other secured debt			$ 10,029

[1] The carrying value excludes deductions for debt issuance costs and discounts.