Fair value measurements (Counterparty Credit Risk) (Detail)
$ in Thousands
Mar. 31, 2017
USD ($)
Financial_Institutions
Dec. 31, 2016
USD ($)
Financial_Institutions
Counterparty Credit Risk    
Derivative liabilities subject to acceleration | $ $ 363  
Predecessor    
Counterparty Credit Risk    
Derivative liabilities subject to acceleration | $   $ 13,553
Concentration of Counterparty Credit Risk    
Counterparty Credit Risk    
Counterparty Credit Risk 4  
Concentration of Counterparty Credit Risk | Predecessor    
Counterparty Credit Risk    
Counterparty Credit Risk   4
Derivative contracts, number of counterparties subject to offset under existing credit facility   4