Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events (Narrative) (Details)

v3.8.0.1
Subsequent Events (Narrative) (Details)
1 Months Ended
Oct. 31, 2017
$ / bbl
bbl
Oct. 11, 2017
USD ($)
Sep. 30, 2017
$ / MMBTU
2018      
Subsequent Event [Line Items]      
Weighted average price (in usd per MMBtu or Bbls) | $ / MMBTU     3.36
Subsequent event | 2026 Notes | Senior notes      
Subsequent Event [Line Items]      
Debt instrument, amount | $   $ 450,000,000.0  
Stated interest rate, percent   6.375%  
Subsequent event | NYMEX WTI | 2018      
Subsequent Event [Line Items]      
Daily volume (in MMBtu or Bbls) | bbl 1,500    
Weighted average price (in usd per MMBtu or Bbls) | $ / bbl 52.05