Annual report pursuant to Section 13 and 15(d)

Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) (Capitalized Costs Related to Oil and Gas Producing Activities) (Details)

v3.3.1.900
Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) (Capitalized Costs Related to Oil and Gas Producing Activities) (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Reserve Quantities [Line Items]    
Proven properties $ 3,606,641 $ 2,457,616
Unproven properties 1,817,701 1,465,538
Capitalized costs, gross 5,424,342 3,923,154
Accumulated depreciation, depletion, amortization and impairment reserve (2,820,113) (1,044,273)
Net capitalized costs 2,604,229 2,878,881
Investment in Grizzly Oil Sands ULC    
Reserve Quantities [Line Items]    
Proven properties 81,473 96,859
Unproven properties 82,388 103,160
Capitalized costs, gross 163,861 200,019
Accumulated depreciation, depletion, amortization and impairment reserve (1,531) (1,248)
Net capitalized costs $ 162,330 $ 198,771