Annual report pursuant to Section 13 and 15(d)

Supplemental Oil and Gas Disclosures - Standardized Measure of Discounted Future Net Cash Flows (Details)

v3.10.0.1
Supplemental Oil and Gas Disclosures - Standardized Measure of Discounted Future Net Cash Flows (Details) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Standardized Measure of Discounted Future Net Cash Flows        
Future cash inflows $ 3,500,900,000 $ 2,328,800,000 $ 1,818,400,000  
Production (958,500,000) (813,800,000) (691,500,000)  
Development (272,400,000) (157,400,000) (141,100,000)  
Dismantlement and abandonment (355,900,000) (361,900,000) (427,700,000)  
Income taxes (293,900,000) [1] (74,800,000) [1] 0  
Future net cash inflows before 10% discount 1,620,200,000 920,900,000 558,100,000  
10% annual discount factor (553,200,000) (180,300,000) (79,800,000)  
Standardized measure of discounted future net cash flows $ 1,067,000,000 $ 740,600,000 $ 478,300,000 $ 613,900,000
[1] No future income taxes were estimated for 2016 as our tax position had sufficient tax basis to offset estimated future taxes. State income taxes were disregarded due to immateriality.