Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized		$ 94	$ 98	$ 103
Deferred Compensation Liability, Current and Noncurrent		189	229
Defined Benefit Plan, Noncash Settlement Loss		6
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation Plan Assets		173	219
Net Periodic Benefit Cost		7	1	1
Accrued benefits liabilities		$ 12	16
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, discount rate		4.10%
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, rate of compensation increase		7.00%
Trading Securities [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation Plan Assets		$ 37	80
Company-Owned Life Insurance Contracts [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation Plan Assets		136	139
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Cost		16	12	$ 12
Accrued benefits liabilities		$ 83	122
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, discount rate		3.60%
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, rate of compensation increase		2.00%
Supplemental Employee Retirement Plans, Defined Benefit [Member] | Available-for-sale Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets in a rabbi trust generally designated to pay benefits of the SERP		$ 99	$ 131
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Noncash Settlement Loss	$ 1