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Supplemental Information on Oil and Gas Exploration and Production Activities (Unaudited) (Tables) | 12 Months Ended
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Dec. 31, 2017
Extractive Industries [Abstract] |
Capitalized Costs Relating to Oil and Gas Producing Activities | Capitalized Costs Related to Oil and Gas Producing Activities
| 2017 |  | 2016
| (In thousands)
Proven properties | $ | 6,256,182 |  |  | $ | 4,491,615 |
Unproven properties | 2,912,974 |  |  | 1,580,305 |
| 9,169,156 |  |  | 6,071,920 |
Accumulated depreciation, depletion, amortization and impairment reserve | (4,136,777 | ) |  | (3,778,043 | )
Net capitalized costs | $ | 5,032,379 |  |  | $ | 2,293,877 |
Equity investment in Grizzly Oil Sands ULC |  |  |
Proven properties | $ | 73,818 |  |  | $ | 70,266 |
Unproven properties | 86,540 |  |  | 80,892 |
| 160,358 |  |  | 151,158 |
Accumulated depreciation, depletion, amortization and impairment reserve | (1,693 | ) |  | (1,578 | )
Net capitalized costs | $ | 158,665 |  |  | $ | 149,580 |
Cost Incurred in Oil and Gas Property Acquisition and Development Activities | Costs Incurred in Oil and Gas Property Acquisition and Development Activities
| 2017 |  | 2016 |  | 2015
| (In thousands)
Acquisition | $ | 1,951,281 |  |  | $ | 152,887 |  |  | $ | 810,755 |
Development of proved undeveloped properties | 994,237 |  |  | 423,998 |  |  | 642,811 |
Exploratory | — |  |  | — |  |  | — |
Recompletions | 14,289 |  |  | 16,386 |  |  | 13,894 |
Capitalized asset retirement obligation | 42,270 |  |  | 10,971 |  |  | 8,800 |
Total | $ | 3,002,077 |  |  | $ | 604,242 |  |  | $ | 1,476,260 |
Equity investment in Grizzly Oil Sands ULC |  |  |  |  |
Acquisition | $ | 503 |  |  | $ | 357 |  |  | $ | 396 |
Development of proved undeveloped properties | — |  |  | — |  |  | 47 |
Exploratory | — |  |  | — |  |  | — |
Capitalized asset retirement obligation | (524 | ) |  | 784 |  |  | 282 |
Total | $ | (21 | ) |  | $ | 1,141 |  |  | $ | 725 |
Results of Operations for Producing Activities | The results of operations exclude general office overhead and interest expense attributable to oil and gas production.
| 2017 |  | 2016 |  | 2015
| (In thousands)
Revenues | $ | 1,320,303 |  |  | $ | 385,910 |  |  | $ | 708,990 |
Production costs | (350,367 | ) |  | (248,125 | ) |  | (222,805 | )
Depletion | (358,792 | ) |  | (243,098 | ) |  | (335,288 | )
Impairment | — |  |  | (715,495 | ) |  | (1,440,418 | )
| 611,144 |  |  | (820,808 | ) |  | (1,289,521 | )
Income tax expense (benefit) |  |  |  |  |
Current | 3,362 |  |  | — |  |  | — |
Deferred | (3,602 | ) |  | — |  |  | (220,201 | )
| (240 | ) |  | — |  |  | (220,201 | )
Results of operations from producing activities | $ | 611,384 |  |  | $ | (820,808 | ) |  | $ | (1,069,320 | )
Depletion per Mcf of gas equivalent (Mcfe) | $ | 0.90 |  |  | $ | 0.92 |  |  | $ | 1.68 |
Results of Operations from equity method investment in Grizzly Oil Sands ULC |  |  |  |  |
Revenues | $ | — |  |  | $ | — |  |  | $ | 1,436 |
Production costs | — |  |  | (13 | ) |  | (1,549 | )
Depletion | — |  |  | — |  |  | (625 | )
| — |  |  | (13 | ) |  | (738 | )
Income tax expense | — |  |  | — |  |  | — |
Results of operations from producing activities | $ | — |  |  | $ | (13 | ) |  | $ | (738 | )
Oil and Gas Reserves | These estimates are reviewed annually and revised, either upward or downward, as warranted by additional performance data.
| 2017 |  | 2016 |  | 2015
| Oil |  | Natural Gas |  | Natural Gas Liquids |  | Oil |  | Natural Gas |  | Natural Gas Liquids |  | Oil |  | Natural Gas |  | Natural Gas Liquids
| (MBbls) |  | (MMcf) |  | (MBbls) |  | (MBbls) |  | (MMcf) |  | (MBbls) |  | (MBbls) |  | (MMcf) |  | (MBbls)
Proved Reserves |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning of the period | 5,546 |  |  | 2,167,068 |  |  | 20,127 |  |  | 6,458 |  |  | 1,560,145 |  |  | 17,736 |  |  | 9,497 |  |  | 719,006 |  |  | 26,268 |
Purchases in oil and natural gas reserves in place | 15,132 |  |  | 1,098,644 |  |  | 53,617 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 371,663 |  |  | — |
Extensions and discoveries | 951 |  |  | 1,594,734 |  |  | 4,619 |  |  | 1,217 |  |  | 1,082,220 |  |  | 7,677 |  |  | 2,413 |  |  | 997,057 |  |  | 5,486 |
Revisions of prior reserve estimates | 107 |  |  | 314,925 |  |  | 2,737 |  |  | (3 | ) |  | (247,703 | ) |  | (1,439 | ) |  | (2,553 | ) |  | (371,430 | ) |  | (9,594 | )
Current production | (2,579 | ) |  | (350,061 | ) |  | (5,334 | ) |  | (2,126 | ) |  | (227,594 | ) |  | (3,847 | ) |  | (2,899 | ) |  | (156,151 | ) |  | (4,424 | )
End of period | 19,157 |  |  | 4,825,310 |  |  | 75,766 |  |  | 5,546 |  |  | 2,167,068 |  |  | 20,127 |  |  | 6,458 |  |  | 1,560,145 |  |  | 17,736 |
Proved developed reserves | 10,245 |  |  | 1,616,930 |  |  | 36,247 |  |  | 4,882 |  |  | 744,797 |  |  | 14,299 |  |  | 6,120 |  |  | 652,961 |  |  | 12,910 |
Proved undeveloped reserves | 8,912 |  |  | 3,208,380 |  |  | 39,519 |  |  | 664 |  |  | 1,422,271 |  |  | 5,828 |  |  | 338 |  |  | 907,184 |  |  | 4,826 |
Equity investment in Grizzly Oil Sands ULC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning of the period | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 14,558 |  |  | — |  |  | — |
Purchases in oil and natural gas reserves in place | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Extensions and discoveries | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Revisions of prior reserve estimates | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (14,530 | ) |  | — |  |  | — |
Current production | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (28 | ) |  | — |  |  | — |
End of period | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Proved developed reserves | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Proved undeveloped reserves | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves | Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves
| Year ended December 31,
| 2017 |  | 2016 |  | 2015
| (In thousands)
Future cash flows | $ | 11,202,692 |  |  | $ | 3,354,168 |  |  | $ | 3,043,450 |
Future development and abandonment costs | (3,005,217 | ) |  | (1,165,025 | ) |  | (877,660 | )
Future production costs | (2,152,821 | ) |  | (924,167 | ) |  | (941,243 | )
Future production taxes | (289,944 | ) |  | (69,447 | ) |  | (58,169 | )
Future income taxes | (573,965 | ) |  | (14,545 | ) |  | (2,648 | )
Future net cash flows | 5,180,745 |  |  | 1,180,984 |  |  | 1,163,730 |
10% discount to reflect timing of cash flows | (2,537,181 | ) |  | (492,944 | ) |  | (399,399 | )
Standardized measure of discounted future net cash flows | $ | 2,643,564 |  |  | $ | 688,040 |  |  | $ | 764,331 |
Equity investment in Grizzly Oil Sands ULC Standardized measure of discounted cash flows |  |  |  |  |
Future cash flows | $ | — |  |  | $ | — |  |  | $ | — |
Future development and abandonment costs | — |  |  | — |  |  | — |
Future production costs | — |  |  | — |  |  | — |
Future production taxes | — |  |  | — |  |  | — |
Future income taxes | — |  |  | — |  |  | — |
Future net cash flows | — |  |  | — |  |  | — |
10% discount to reflect timing of cash flows |  |  |  |  |  |  |  |
Standardized measure of discounted future net cash flows | $ | — |  |  | $ | — |  |  | $ | — |
Changes in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves | Changes in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves
| Year ended December 31,
| 2017 |  | 2016 |  | 2015
| (In thousands)
Sales and transfers of oil and gas produced, net of production costs | $ | (756,257 | ) |  | $ | (312,291 | ) |  | $ | (486,185 | )
Net changes in prices, production costs, and development costs | 913,714 |  |  | (146,518 | ) |  | (1,412,181 | )
Acquisition of oil and gas reserves in place | 703,866 |  |  | — |  |  | 83,340 |
Extensions and discoveries | 618,039 |  |  | 186,909 |  |  | 262,895 |
Previously estimated development costs incurred during the period | 390,673 |  |  | 176,218 |  |  | 117,540 |
Revisions of previous quantity estimates, less related production costs | 155,200 |  |  | (38,448 | ) |  | (98,162 | )
Accretion of discount | 68,804 |  |  | 76,433 |  |  | 142,717 |
Net changes in income taxes | (231,545 | ) |  | (6,495 | ) |  | 412,240 |
Change in production rates and other | 93,030 |  |  | (12,099 | ) |  | 314,960 |
Total change in standardized measure of discounted future net cash flows | $ | 1,955,524 |  |  | $ | (76,291 | ) |  | $ | (662,836 | )
Equity investment in Grizzly Oil Sands ULC Changes in standardized measure of discounted cash flows |  |  |  |  |
Sales and transfers of oil and gas produced, net of production costs | $ | — |  |  | $ | — |  |  | $ | 114 |
Net changes in prices, production costs, and development costs | — |  |  | — |  |  | — |
Acquisition of oil and gas reserves in place | — |  |  | — |  |  | — |
Extensions and discoveries | — |  |  | — |  |  | — |
Previously estimated development costs incurred during the period | — |  |  | — |  |  | 47 |
Revisions of previous quantity estimates, less related production costs | — |  |  | — |  |  | (103,282 | )
Accretion of discount | — |  |  | — |  |  | 9,375 |
Net changes in income taxes | — |  |  | — |  |  | — |
Change in production rates and other | — |  |  | — |  |  | — |
Total change in standardized measure of discounted future net cash flows | $ | — |  |  | $ | — |  |  | $ | (93,746 | )

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- Definition Tabular disclosure of the net quantities of an enterprise's interests in proved developed and undeveloped reserves of (a) crude oil (including condensate and natural gas liquids), (b) natural gas (including coal bed methane), (c) synthetic oil, (d) synthetic gas, and (e) other nonrenewable natural resources that are intended to be upgraded during the period as of the beginning of the period, changes in quantities during the period, and as of the end of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61858-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61884-109447 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61797-109447 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61869-109447 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61872-109447 + Details
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- Definition Tabular disclosure of the future net cash flows relating to proved oil and gas reserves and oil and gas subject to purchase under long-term agreements in which the enterprise participates in the operation of the properties on which the oil and gas is located or otherwise serves as the producer. This information is presented in aggregate and for each geographic area for which reserve quantities are disclosed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 30 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62424-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62476-109447 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 36 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62536-109447 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 35 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62500-109447 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 31 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62455-109447 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62479-109447 + Details
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