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Asset Retirement Obligations | 12 Months Ended
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Dec. 31, 2017
Asset Retirement Obligations [Abstract] |
Asset Retirement Obligations | ﻿ Note H – Asset Retirement Obligations The asset retirement obligations liabilities (ARO) recognized by the Company at December 31, 2017 and 2016 are related to the estimated costs to dismantle and abandon its producing oil and gas properties and related equipment. ﻿ A reconciliation of the beginning and ending aggregate carrying amount of the asset retirement obligation for 2017 and 2016 is shown in the following table. ﻿ ﻿
﻿ |  |  |  |
﻿ |  |  |  |
﻿(Thousands of dollars) | 2017 |  | 2016
﻿Balance at beginning of year | $ | 781,057 |  | 825,312
﻿ Accretion expense |  | 42,590 |  | 46,742
﻿ Liabilities incurred |  | 52,331 |  | 13,690
﻿ Revisions of previous estimates |  | (47,612) |  | (4,511)
﻿ Liabilities settled |  | (29,111) |  | (20,589)
﻿ Liabilities assumed by purchaser of oil and gas assets |  | (87,456) |  | (91,883)
﻿ Changes due to translation of foreign currencies |  | 10,340 |  | 12,296
﻿ Balance at end of year |  | 722,139 |  | 781,057
﻿ Liabilities reported as held for sale at end of year 1 |  | – |  | (85,900)
﻿ Current portion of liability at end of year 2 |  | (12,840) |  | (13,629)
﻿ Noncurrent portion of liability at end of year | $ | 709,299 |  | 681,528
﻿ 1 Liabilities held for sale related to Seal properties in Canada which were sold in January 2017. 2 Included in Other accrued liabilities on the Consolidated Balance Sheet. ﻿ The estimation of future ARO is based on a number of assumptions requiring professional judgment. The Company cannot predict the type of revisions to these assumptions that may be required in future periods due to the availability of additional information such as: prices for oil field services, technological changes, governmental requirements and other factors. ﻿ In 2017, revisions of previous estimates primarily reflect the impact of lower rig service rates in the U.S.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -URI http://asc.fasb.org/subtopic&trid=2175671 + Details
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