Retirement and Deferred Compensation Plans (Benefit Plans' Assets and Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,566	$ 1,433
Projected benefit obligation	1,674	1,593
Funded status of plan	(108)	(160)
Amounts Recognized on the Consolidated Balance Sheets
Other assets	45	26
Other liabilities	(153)	(186)
Net amount recognized	$ (108)	$ (160)
Weighted-Average Assumptions, Benefit obligations:
Weighted-average discount rate	3.62%	4.03%
Weighted-Average Assumptions, Net periodic benefit cost:
Weighted-average discount rate	4.01%	4.29%
Expected return on plan assets	6.71%	6.99%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 60	$ 56
Projected benefit obligation	87	84
Funded status of plan	(27)	(28)
Amounts Recognized on the Consolidated Balance Sheets
Other liabilities	(27)	(28)
Net amount recognized	$ (27)	$ (28)
Weighted-Average Assumptions, Benefit obligations:
Weighted-average discount rate	4.00%	4.50%
Weighted-Average Assumptions, Net periodic benefit cost:
Weighted-average discount rate	4.50%	4.50%
Expected return on plan assets	6.50%	6.50%