Retirement And Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 13	$ 14	$ 11
Interest cost	5	4	4
Expected return on plan assets	(7)	(6)	(5)
Amortization of transition obligation
Amortization of prior service cost
Amortization of net loss	1	2	1
Net periodic benefit cost	12	14	11
Settlements and curtailments		0
Total benefit cost	12	14	11
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	2
Interest cost	1	1
Amortization of transition obligation
Amortization of prior service cost
Net periodic benefit cost	3	3	2
Total benefit cost	$ 3	$ 3	$ 2