v3.3.1.900
Disclosures About Oil and Gas Producing Activities - Summary of Changes in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Natural Gas Reserves (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Extractive Industries [Abstract]      
Standardized measure of discounted future net cash flows, Beginning balance $ 1,055,815 $ 676,277 $ 494,220
Net change in sales and transfer prices and in production (lifting) costs related to future production (1,405,864) (59,920) 74,088
Changes in estimated future development costs 231,900 (388,772) (301,132)
Sales and transfers of oil and gas produced during the period (91,278) (209,893) (149,310)
Net change due to extensions, discoveries and improved recovery 156,783 534,231 360,080
Net change due to purchase of minerals in place     1,435
Net change due to revisions in quantity estimates (59,305) (78,801) (61,931)
Previously estimated development costs incurred during the period 146,237 382,995 287,898
Accretion of discount 105,582 113,188 87,937
Other 6,915 (11,897) 1,896
Net change in income taxes 313,610 98,407 (118,904)
Standardized Measure of discounted future net cash flows $ 460,395 $ 1,055,815 $ 676,277