Retirement And Employee Benefit Plans (Amounts Recognized In Other Comprehensive Income) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain arising during the year	$ (13)
Amortization of prior service cost
Amortization of net loss	20
Settlements
Tax effect	(3)
Total	4
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain arising during the year	2
Amortization of prior service cost
Amortization of net loss
Settlements	1
Tax effect	(1)
Total	$ 2