Significant Accounting Policies (Impair and Pensions) (Details) $ / shares in Units, $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) item $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares
Long-Live assets
Loss associated with impairment	$ 52	$ 668	$ 507
Goodwill
Goodwill impairment loss						$ 3,000
Loss on impairment of goodwill, tax effect						0
Loss on impairment of goodwill attributable to controlling interest						$ 2,900
Loss on impairment of goodwill per diluted share from continuing operations | $ / shares						$ 8.02
Loss on impairment of goodwill attributable to noncontrolling interest						$ 74
Pension and other postretirement benefits
Recognition period of investment gains or losses related to asset valuation for determining net periodic benefit cost				5 years
Conditional amortization gains or losses as percentage of greater of plan assets or liabilities, minimum				10.00%
Number of critical fair value assumptions | item				2
Pension liability, current and noncurrent	375			$ 375	$ 414
Pension asset, non-current	$ 5			5	2
Net periodic benefit costs				11	26	75
Construction in Progress
Long-Live assets
Loss associated with impairment					52
Deepwater Floater asset group
Long-Live assets
Loss associated with impairment				$ 52	507	788
Loss associated with impairment, net of tax					$ 481	$ 693
Loss associated with impairment per diluted share | $ / shares				$ 0.14	$ 1.31	$ 1.91
Midwater Floater asset group
Long-Live assets
Loss associated with impairment					$ 668
Loss associated with impairment, net of tax					$ 654
Loss associated with impairment per diluted share | $ / shares					$ 1.78