Exit and Disposal Costs	12 Months Ended
Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Exit and Disposal Costs	12. Exit and Disposal Costs In 2018, we incurred severance expense of $38 million (2017: $18 million; 2016: $55 million) and paid accrued severance costs of $40 million (2017: $48 million; 2016: $52 million). The severance expenses incurred during the three-year period resulted from asset sales and cost savings initiatives in response to low crude oil prices. Severance charges were based on amounts incurred under ongoing severance arrangements or other statutory requirements, plus amounts earned under enhanced benefit arrangements. We recognized the expense associated with the enhanced benefits ratably over the estimated service period required for the employee to earn the benefit upon termination. We also recorded charges for vacated office space of $73 million in 2018 (2017: $14 million). At December 31, 2018, we had accrued liabilities for severance costs of $4 million (2017: $6 million) and accrued liabilities for exit cost provisions of $85 million (2017: $28 million). Accrued severance costs are expected to be paid in 2019, and accrued exit costs will be paid over the next several years.

Exit and Disposal Costs

12 Months Ended

Dec. 31, 2018

Restructuring And Related Activities [Abstract]

12. Exit and Disposal Costs

In 2018, we incurred severance expense of $38 million (2017: $18 million; 2016: $55 million) and paid accrued severance costs of $40 million (2017: $48 million; 2016: $52 million). The severance expenses incurred during the three-year period resulted from asset sales and cost savings initiatives in response to low crude oil prices. Severance charges were based on amounts incurred under ongoing severance arrangements or other statutory requirements, plus amounts earned under enhanced benefit arrangements. We recognized the expense associated with the enhanced benefits ratably over the estimated service period required for the employee to earn the benefit upon termination. We also recorded charges for vacated office space of $73 million in 2018 (2017: $14 million).

At December 31, 2018, we had accrued liabilities for severance costs of $4 million (2017: $6 million) and accrued liabilities for exit cost provisions of $85 million (2017: $28 million). Accrued severance costs are expected to be paid in 2019, and accrued exit costs will be paid over the next several years.