Annual report pursuant to Section 13 and 15(d)

Supplemental Disclosures About Natural Gas Producing Activities - Standardized Measure of Discounted Future Net Cash Flows Related to Proved Natural Gas & Condensate Reserves (Details)

v3.10.0.1
Supplemental Disclosures About Natural Gas Producing Activities - Standardized Measure of Discounted Future Net Cash Flows Related to Proved Natural Gas & Condensate Reserves (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Extractive Industries [Abstract]      
Future cash inflows $ 676,454 $ 777,711  
Future production costs (105,341) (144,991)  
Future development costs (264,239) (331,297)  
Future income tax provisions (54,564) (52,212)  
Future net cash flows 252,310 249,211  
Less effect of a 10% discount factor (106,499) (161,009)  
Standardized measure of discounted future net cash flows $ 145,811 $ 88,202 $ 0