Employee Retirement Benefits (Components Of Net Periodic Benefit Cost As Well As Other Changes In Plan Assets And Benefit Obligations Recognized In Other Comprehensive Income For Qualified Plan And SERP) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 12	$ 10	$ 13
Interest cost	14	15	13
Expected return on plan assets	(18)	(17)	(17)
Amortization of actuarial loss and prior service cost	6	2	9
Other	1	3	2
Net periodic benefit cost	15	13	20
Current year actuarial loss (gain)	13	21	(72)
Amortization of actuarial loss	6	5	10
Other	0	2	0
Amortization of prior service cost	(1)	0	(1)
Total recognized in other comprehensive loss (income)	$ 6	$ 18	$ (83)