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Guarantees (Details) - USD ($) $ in Millions	9 Months Ended
Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Environmental accruals for known contamination in carrying amount recorded for indemnifications	$ 163.0	$ 178.0
Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Ownership percentage in equity investment	37.50%
Continued development [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 130.0
Continued development [Member] \| Australia Pacific APLNG [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of guarantees outstanding	up to 26 years or the life of the venture
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 800.0
Other Guarantees [Member] \| U.K. Subsidiaries [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 148.0
Other Guarantees [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of guarantees outstanding	up to three years
Indemnifications [Member]
Guarantor Obligations [Line Items]
Environmental accruals for known contamination in carrying amount recorded for indemnifications	$ 30.0
Guarantor Obligations, Current Carrying Value	$ 90.0
Guarantee existing sales agreement of natural gas delivery \| Australia Pacific APLNG [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of guarantees outstanding	up to 23 years
Max potential future payments-reckless breach [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 1,300.0
Max potential future payments-prorata share [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	720.0
Finance Reserve Guarantee [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 170.0
Terms of guarantees outstanding	11 years
Guarantor Obligations, Current Carrying Value	$ 14.0