Retirement And Employee Benefit Plans (Fair Value Measurement Of Pension Plan Assets) (Details) - Pension Benefits [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 81	$ 108	$ 108
Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67	59
Excluding Net Assets Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67	59
Net Asset Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	49
Equity Securities [Member] | U.S. Large Cap Growth Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	9
Equity Securities [Member] | U.S. Large Cap Growth Equity [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	9
Equity Securities [Member] | U.S. Large Cap Value Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	9
Equity Securities [Member] | U.S. Large Cap Value Equity [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	9
Equity Securities [Member] | U.S. Large Cap Core Equity [Member] | Net Asset Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	18
Equity Securities [Member] | U.S. Small Cap Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3
Equity Securities [Member] | U.S. Small Cap Equity [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3
Equity Securities [Member] | Non-U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	31
Equity Securities [Member] | Non-U.S. Equity [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	31
Equity Securities [Member] | Emerging Markets Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Equity Securities [Member] | Emerging Markets Equity [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21
Fixed Income [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21
Fixed Income [Member] | Net Asset Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		31
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	2
Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4	$ 2