Supplemental Oil and Gas Disclosures (Unaudited) (Details) (USD $) | 12 Months Ended |
In Thousands, unless otherwise specified | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 |
Capitalized costs relating to oil and gas producing activities [Abstract] | ' | ' | ' |
Proved oil and gas properties | $564,755 | $563,317 | ' |
Unproved properties | 0 | 2,089 | ' |
Total | 564,755 | 565,406 | ' |
Accumulated depreciation, depletion, amortization and impairment | -413,704 | -383,469 | ' |
Net capitalized costs | 151,051 | 181,937 | ' |
Cost incurred in oil and gas property acquisition and development activities [Abstract] | ' | ' | ' |
Development costs | 93,878 | 56,318 | 46,735 |
Exploration costs | 0 | 0 | 8,410 |
Property acquisition costs | 0 | 7,200 | 0 |
Unproved | 0 | 989 | 1,100 |
Total | 93,878 | 64,507 | 56,245 |
Results of operations for oil and gas producing activities [Abstract] | ' | ' | ' |
Revenues | 94,275 | 68,499 | 64,615 |
Production costs | -33,871 | -31,419 | -27,347 |
Depreciation, depletion, and amortization | -26,072 | -22,767 | -15,595 |
Proved property impairment | -6,025 | -19,774 | 0 |
General and administrative | -3,350 | -2,679 | -2,352 |
Results of operations from oil and gas producing activities (excluding corporate overhead and interest costs) | 24,957 | -8,140 | 19,321 |
Depletion per barrel of oil equivalent | 16.59 | 15.59 | 12.26 |
Oil/NGL [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 19,956,000 | 14,219,000 | 9,794,000 |
Revisions of previous estimates | 999,000 | 1,574,000 | 2,290,000 |
Extensions and discoveries | 10,746,000 | 5,809,000 | 2,703,000 |
Purchases of minerals in place | 0 | 1,000 | ' |
Sales of minerals in place | -7,748,000 | -850,000 | 0 |
Production | 1,000,000 | 797,000 | 568,000 |
Balance | 22,953,000 | 19,956,000 | 14,219,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 8,310,000 | 8,650,000 | 7,761,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 14,640,000 | 11,306,000 | 6,460,000 |
Natural Gas [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 61,184,000 | 72,075,000 | 84,913,000 |
Revisions of previous estimates | -5,123,000 | -7,470,000 | -13,009,000 |
Extensions and discoveries | 3,610,000 | 6,983,000 | 4,393,000 |
Purchases of minerals in place | 0 | 69,000 | ' |
Sales of minerals in place | -8,141,000 | -6,376,000 | 0 |
Production | 3,421,000 | 4,097,000 | 4,222,000 |
Balance | 48,109,000 | 61,184,000 | 72,075,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 31,572,000 | 41,220,000 | 42,582,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 16,537,000 | 19,964,000 | 29,493,000 |
Oil Equivalents [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 30,152,000 | 26,232,000 | 23,947,000 |
Revisions of previous estimates | 145,000 | 328,000 | 122,000 |
Extensions and discoveries | 11,348,000 | 6,973,000 | 3,435,000 |
Purchases of minerals in place | 0 | 13,000 | ' |
Sales of minerals in place | -9,105,000 | -1,913,000 | 0 |
Production | 1,570,000 | 1,481,000 | 1,272,000 |
Balance | 30,970,000 | 30,152,000 | 26,232,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 13,572,000 | 15,520,000 | 14,858,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 17,397,000 | 14,634,000 | 11,376,000 |
U.S. [Member] | ' | ' | ' |
Capitalized costs relating to oil and gas producing activities [Abstract] | ' | ' | ' |
Proved oil and gas properties | 530,996 | 531,971 | ' |
Unproved properties | 0 | 0 | ' |
Total | 530,996 | 531,971 | ' |
Accumulated depreciation, depletion, amortization and impairment | -381,283 | -356,255 | ' |
Net capitalized costs | 149,713 | 175,716 | ' |
Cost incurred in oil and gas property acquisition and development activities [Abstract] | ' | ' | ' |
Development costs | 91,325 | 48,283 | 32,471 |
Exploration costs | 0 | 0 | 8,410 |
Property acquisition costs | 0 | 7,200 | 0 |
Unproved | 0 | 0 | 0 |
Total | 91,325 | 55,483 | 40,881 |
Results of operations for oil and gas producing activities [Abstract] | ' | ' | ' |
Revenues | 92,268 | 65,590 | 63,105 |
Production costs | -31,642 | -29,166 | -26,552 |
Depreciation, depletion, and amortization | -25,028 | -20,704 | -14,914 |
Proved property impairment | 0 | 0 | 0 |
General and administrative | -2,471 | -1,980 | -1,698 |
Results of operations from oil and gas producing activities (excluding corporate overhead and interest costs) | 33,127 | 13,740 | 19,941 |
Depletion per barrel of oil equivalent | 16.32 | 14.74 | 11.96 |
U.S. [Member] | Oil/NGL [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 19,751,000 | 13,780,000 | 9,718,000 |
Revisions of previous estimates | 1,073,000 | 1,774,000 | 2,290,000 |
Extensions and discoveries | 10,746,000 | 5,809,000 | 2,326,000 |
Purchases of minerals in place | 0 | 1,000 | ' |
Sales of minerals in place | -7,748,000 | -850,000 | 0 |
Production | 976,000 | 763,000 | 554,000 |
Balance | 22,846,000 | 19,751,000 | 13,780,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 8,284,000 | 8,531,000 | 7,433,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 14,560,000 | 11,220,000 | 6,348,000 |
U.S. [Member] | Natural Gas [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 60,099,000 | 69,191,000 | 84,523,000 |
Revisions of previous estimates | -4,804,000 | -5,786,000 | -13,009,000 |
Extensions and discoveries | 3,610,000 | 6,983,000 | 1,837,000 |
Purchases of minerals in place | 0 | 69,000 | ' |
Sales of minerals in place | -8,141,000 | -6,376,000 | 0 |
Production | 3,343,000 | 3,982,000 | 4,160,000 |
Balance | 47,421,000 | 60,099,000 | 69,191,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 31,424,000 | 40,723,000 | 40,451,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 15,996,000 | 19,376,000 | 28,740,000 |
U.S. [Member] | Oil Equivalents [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 29,768,000 | 25,313,000 | 23,806,000 |
Revisions of previous estimates | 270,000 | 809,000 | 122,000 |
Extensions and discoveries | 11,348,000 | 6,973,000 | 2,632,000 |
Purchases of minerals in place | 0 | 13,000 | ' |
Sales of minerals in place | -9,105,000 | -1,913,000 | 0 |
Production | 1,533,000 | 1,427,000 | 1,247,000 |
Balance | 30,748,000 | 29,768,000 | 25,313,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 13,521,000 | 15,318,000 | 14,175,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 17,226,000 | 14,450,000 | 11,138,000 |
Canada [Member] | ' | ' | ' |
Capitalized costs relating to oil and gas producing activities [Abstract] | ' | ' | ' |
Proved oil and gas properties | 33,759 | 31,346 | ' |
Unproved properties | 0 | 2,089 | ' |
Total | 33,759 | 33,435 | ' |
Accumulated depreciation, depletion, amortization and impairment | -32,421 | -27,214 | ' |
Net capitalized costs | 1,338 | 6,221 | ' |
Cost incurred in oil and gas property acquisition and development activities [Abstract] | ' | ' | ' |
Development costs | 2,553 | 8,035 | 14,264 |
Exploration costs | 0 | 0 | 0 |
Property acquisition costs | 0 | 0 | 0 |
Unproved | 0 | 989 | 1,100 |
Total | 2,553 | 9,024 | 15,364 |
Results of operations for oil and gas producing activities [Abstract] | ' | ' | ' |
Revenues | 2,007 | 2,909 | 1,510 |
Production costs | -2,229 | -2,253 | -795 |
Depreciation, depletion, and amortization | -1,044 | -2,063 | -681 |
Proved property impairment | -6,025 | -19,774 | 0 |
General and administrative | -879 | -699 | -654 |
Results of operations from oil and gas producing activities (excluding corporate overhead and interest costs) | ($8,170) | ($21,880) | ($620) |
Depletion per barrel of oil equivalent | 27.37 | 37.48 | 27.58 |
Canada [Member] | Oil/NGL [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 205,000 | 439,000 | 76,000 |
Revisions of previous estimates | -74,000 | -200,000 | 0 |
Extensions and discoveries | 0 | 0 | 377,000 |
Purchases of minerals in place | 0 | 0 | ' |
Sales of minerals in place | 0 | 0 | 0 |
Production | 24,000 | 34,000 | 14,000 |
Balance | 107,000 | 205,000 | 439,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 26,000 | 119,000 | 328,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 80,000 | 86,000 | 112,000 |
Canada [Member] | Natural Gas [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 1,085,000 | 2,884,000 | 390,000 |
Revisions of previous estimates | -319,000 | -1,684,000 | 0 |
Extensions and discoveries | 0 | 0 | 2,556,000 |
Purchases of minerals in place | 0 | 0 | ' |
Sales of minerals in place | 0 | 0 | 0 |
Production | 78,000 | 115,000 | 62,000 |
Balance | 688,000 | 1,085,000 | 2,884,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 148,000 | 497,000 | 2,131,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 541,000 | 588,000 | 753,000 |
Canada [Member] | Oil Equivalents [Member] | ' | ' | ' |
Proved developed and undeveloped reserves [Abstract] | ' | ' | ' |
Balance | 384,000 | 919,000 | 141,000 |
Revisions of previous estimates | -125,000 | -481,000 | 0 |
Extensions and discoveries | 0 | 0 | 803,000 |
Purchases of minerals in place | 0 | 0 | ' |
Sales of minerals in place | 0 | 0 | 0 |
Production | 37,000 | 54,000 | 25,000 |
Balance | 222,000 | 384,000 | 919,000 |
Proved Developed Reserves [Abstract] | ' | ' | ' |
Proved Developed Reserves | 51,000 | 202,000 | 683,000 |
Proved Undeveloped Reserves [Abstract] | ' | ' | ' |
Proved Undeveloped Reserves | 171,000 | 184,000 | 238,000 |