Retirement Plans (Retirement Plans, Funded Status) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Expense for the defined contribution plans for continuing operations		$ 193	$ 173	$ 111
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan		39	2
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at end of period		951	1,200
Fair value of plan assets at end of period		832	940
Funded status at end of period		119	280
Amounts recognized on the Consolidated Balance Sheets
Accrued employee compensation and benefits		8	15
Employee compensation and benefits		150	267
Pension plans in which projected benefit obligation exceeded plan assets
Projected benefit obligation (a)	[1]	176	1,202
Fair value of plan assets		18	920
Pension plans in which accumulated benefit obligation exceeded plan assets
Accumulated benefit obligation (a)	[1]	105	1,139
Fair value of plan assets		18	920
Defined Benefit Plan, Accumulated Benefit Obligation		878	1,200
Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		12	11
Foreign Plan [Member] | Equity funds (b)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[3]	137	204
Foreign Plan [Member] | Bond funds (c)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[4]	323	369
Foreign Plan [Member] | alternatives fund [Domain]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[5]	209	184
Foreign Plan [Member] | Real Estate Funds [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[6]	109	126
Foreign Plan [Member] | Other assets
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		42	46
Foreign Plan [Member] | Level 1
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		6	7
Foreign Plan [Member] | Level 1 | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		0	0
Foreign Plan [Member] | Level 1 | Equity funds (b)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[3]	0	0
Foreign Plan [Member] | Level 1 | Bond funds (c)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[4]	0	0
Foreign Plan [Member] | Level 1 | alternatives fund [Domain]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[5]	0	0
Foreign Plan [Member] | Level 1 | Real Estate Funds [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[6]	0	0
Foreign Plan [Member] | Level 1 | Other assets
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		6	7
Foreign Plan [Member] | Level 2
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		762	842
Foreign Plan [Member] | Level 2 | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		12	11
Foreign Plan [Member] | Level 2 | Equity funds (b)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[3]	137	204
Foreign Plan [Member] | Level 2 | Bond funds (c)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[4]	302	323
Foreign Plan [Member] | Level 2 | alternatives fund [Domain]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[5]	209	184
Foreign Plan [Member] | Level 2 | Real Estate Funds [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[6]	81	98
Foreign Plan [Member] | Level 2 | Other assets
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		21	22
Foreign Plan [Member] | Level 3
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		64	91
Foreign Plan [Member] | Level 3 | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		0	0
Foreign Plan [Member] | Level 3 | Equity funds (b)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[3]	0	0
Foreign Plan [Member] | Level 3 | Bond funds (c)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[4]	21	46
Foreign Plan [Member] | Level 3 | alternatives fund [Domain]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[5]	0	0
Foreign Plan [Member] | Level 3 | Real Estate Funds [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period	[2],[6]	28	28
Foreign Plan [Member] | Level 3 | Other assets
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Fair value of plan assets at end of period		$ 15	$ 17
United Kingdom Pension Plan [Member]
Pension plans in which accumulated benefit obligation exceeded plan assets
United Kingdom pension plan percentage of international pension plans' projected benefit obligations		80.00%

[1] Our United Kingdom pension plan was underfunded as of December 31, 2017 and overfunded as of December 31, 2018. As such, the fair value of plan assets and projected and accumulated benefit obligation related to this plan are no longer captured in this table at December 31, 2018.

[2] Common/collective trust funds are valued at the net asset value of units held by the plans at year-end.

[3] Strategy is to invest in diversified funds of global common stocks.

[4] Strategy is to invest in diversified funds of fixed income securities of varying geographies and credit quality and whose cash flows approximate the maturities of the benefit obligation.

[5] Strategy is to invest in a fund of diversifying investments, including but not limited to reinsurance, commodities and currencies.

[6] Strategy is to invest in diversified funds of real estate investment trusts and private real estate.