Pension and Other Postretirement Employee Benefit Plans - Defined Benefit Pension Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plan, benefit obligation expense retirement plan	$ 215,000,000	$ 237,000,000
Defined contribution plans
Employer matching percent of employees' gross pay	5.00%
Employee annual compensation amount not eligible for employers matching contributions	$ 250,000
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Period after which employees begin to accrue plan benefits	1 year
Period after which benefits generally vest	3 years
Defined contribution plans
Period after which employees begin to receive matching contributions	1 year
Period after which matching contributions vest	3 years
Funded status of plan - supplemental information
Unfunded postretirement benefit obligation, U.K. Plan	$ 35,000,000	32,000,000
U.S. defined benefit pension plans
Change in benefit obligation
Benefit obligation, beginning of year	(11,912,000,000)	(12,536,000,000)
Benefits earned during the year	(296,000,000)	(340,000,000)	$ (281,000,000)
Interest cost on benefit obligations	(530,000,000)	(498,000,000)	(534,000,000)
Special termination benefits	0	0
Net gain/(loss)	(203,000,000)	702,000,000
Benefits paid	725,000,000	760,000,000
Plan settlements	0	0
Foreign exchange impact and other	0	0
Benefit obligation, end of year	(12,216,000,000)	(11,912,000,000)	(12,536,000,000)
Change in plan assets
Fair value of plan assets, beginning of year	14,125,000,000	14,623,000,000
Actual return on plan assets	838,000,000	231,000,000
Firm contributions	34,000,000	31,000,000
Employee contributions	0	0
Benefits paid	(725,000,000)	(760,000,000)
Plan settlements	0	0
Foreign exchange impact and other	0	0
Fair value of plan assets, end of year	14,272,000,000	14,125,000,000	14,623,000,000
Net funded status	2,056,000,000	2,213,000,000
Accumulated benefit obligation, end of year	(12,062,000,000)	(11,774,000,000)
U.S. defined benefit pension plans | Participation rights under participating annuity contracts
Change in plan assets
Fair value of plan assets, beginning of year	533,000,000
Fair value of plan assets, end of year	390,000,000	533,000,000
U.S. defined benefit pension plans | Accrued receivables
Funded status of plan - supplemental information
Defined benefit plans, amounts not measured at fair value	130,000,000	74,000,000
U.S. defined benefit pension plans | Accrued liabilities
Funded status of plan - supplemental information
Defined benefit plans, amounts not measured at fair value	224,000,000	123,000,000
Non-U.S. defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plan, estimated future employer contributions in next fiscal year	44,000,000
Defined benefit plan, contractually required future employer contributions in next fiscal year	28,000,000
Change in benefit obligation
Benefit obligation, beginning of year	(3,347,000,000)	(3,640,000,000)
Benefits earned during the year	(36,000,000)	(37,000,000)	(33,000,000)
Interest cost on benefit obligations	(99,000,000)	(112,000,000)	(137,000,000)
Special termination benefits	0	(1,000,000)
Employee contributions	(7,000,000)	(7,000,000)
Net gain/(loss)	(540,000,000)	146,000,000
Benefits paid	126,000,000	120,000,000
Plan settlements	21,000,000	0
Foreign exchange impact and other	504,000,000	184,000,000
Benefit obligation, end of year	(3,378,000,000)	(3,347,000,000)	(3,640,000,000)
Change in plan assets
Fair value of plan assets, beginning of year	3,511,000,000	3,718,000,000
Actual return on plan assets	537,000,000	52,000,000
Firm contributions	52,000,000	45,000,000
Employee contributions	7,000,000	7,000,000
Benefits paid	(126,000,000)	(120,000,000)
Plan settlements	(21,000,000)	0
Foreign exchange impact and other	(529,000,000)	(191,000,000)
Fair value of plan assets, end of year	3,431,000,000	3,511,000,000	3,718,000,000
Net funded status	53,000,000	164,000,000
Accumulated benefit obligation, end of year	(3,359,000,000)	(3,322,000,000)
OPEB plans
Change in benefit obligation
Benefit obligation, beginning of year	(744,000,000)	(842,000,000)
Benefits earned during the year	0	(1,000,000)	0
Interest cost on benefit obligations	(31,000,000)	(31,000,000)	(38,000,000)
Special termination benefits	0	0
Employee contributions	(19,000,000)	(25,000,000)
Net gain/(loss)	4,000,000	71,000,000
Benefits paid	76,000,000	88,000,000
Plan settlements	0	0
Expected Medicare Part D subsidy receipts	0	(6,000,000)
Foreign exchange impact and other	6,000,000	2,000,000
Benefit obligation, end of year	(708,000,000)	(744,000,000)	(842,000,000)
Change in plan assets
Fair value of plan assets, beginning of year	1,855,000,000	1,903,000,000
Actual return on plan assets	131,000,000	13,000,000
Firm contributions	2,000,000	2,000,000
Employee contributions	0	0
Benefits paid	(32,000,000)	(63,000,000)
Plan settlements	0	0
Foreign exchange impact and other	0	0
Fair value of plan assets, end of year	1,956,000,000	1,855,000,000	$ 1,903,000,000
Net funded status	1,248,000,000	1,111,000,000
OPEB plans | Overfunded plans
Change in plan assets
Net funded status	4,000,000,000	4,100,000,000
OPEB plans | Underfunded plans
Change in plan assets
Net funded status	$ 639,000,000	$ 636,000,000