Retirement Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expenses	$ 63	$ 56	$ 52
Multi-employer plan contribution	0	0	$ 3
Funded amount	10	8
Employee deferred compensation plan	$ 65	67
United States
Defined Benefit Plan Disclosure [Line Items]
Number of frozen defined benefit plans | plan	2
Increase in projected benefit obligation	$ 0	0
Accumulated benefit obligation	$ 76	71
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Number of frozen defined benefit plans | plan	1
Increase in prior service cost		20
Increase in projected benefit obligation		20
Germany
Defined Benefit Plan Disclosure [Line Items]
Number of frozen defined benefit plans | plan	1
Int’l
Defined Benefit Plan Disclosure [Line Items]
Increase in projected benefit obligation	$ 0	20
Accumulated benefit obligation	$ 2,000	$ 1,800
Scenario, Forecast | Int’l
Defined Benefit Plan Disclosure [Line Items]
Estimated employer contributions in next fiscal year				$ 47