Asset Retirement Obligations and Accrued Environmental Costs (Tables)	12 Months Ended
	Dec. 31, 2021
Asset Retirement Obligations and Accrued Environmental Costs [Abstract]
Asset Retirement Obligations and Accrued Environmental Costs	Asset retirement obligations and accrued environmental costs at December 31 were: Millions of Dollars 2021 2020 Asset retirement obligations $ 5,926 5,573 Accrued environmental costs 187 180 Total asset retirement obligations and accrued environmental costs 6,113 5,753 Asset retirement obligations and accrued environmental costs due within one year* (359) (323) Long-term asset retirement obligations and accrued environmental costs $ 5,754 5,430 *Classified as a current liability on the balance sheet under “Other accruals.”
Changes in Asset Retirement Obligation	During 2021 and 2020, our overall ARO changed as follows: Millions of Dollars 2021 2020 Balance at January 1 $ 5,573 6,206 Accretion of discount 238 248 New obligations 555 262 Changes in estimates of existing obligations (113) (307) Spending on existing obligations (164) (116) Property dispositions (108) (771) Foreign currency translation (55) 51 Balance at December 31 $ 5,926 5,573