Employee Benefit Plans Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Estimated contributions next fiscal year	$ 6
Postemployment Benefits
Postemployment benefit income (expense)	4		$ 2		$ 1
Postemployment Benefits Liability, Noncurrent	14		12
Benefit expense related to deferred compensation plans	1		1		1
Other Postretirement Benefit Plans, Defined Benefit [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	25		26		$ 26
Expected Future Benefit Payments, Fiscal Year Maturity
Benefit Payments - 2016	10
Benefit Payments - 2017	10
Benefit Payments - 2018	10
Benefit Payments - 2019	11
Benefit Payments - 2020	11
Benefit Payments - 2021-2025	56
Medicare Subsidy Receipts - 2016	(2)
Medicare Subsidy Receipts - 2017	(2)
Medicare Subsidy Receipts - 2018	(2)
Medicare Subsidy Receipts - 2019	(2)
Medicare Subsidy Receipts - 2020	(3)
Medicare Subsidy Receipts - 2021-2025	$ (17)
Other Postretirement Benefit Plans, Defined Benefit [Member] | U.S. Equity [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	15.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	25.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | International Equity [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	2.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	12.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fixed Income [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	68.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	78.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	2.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	$ 25	[1]	26	[2]
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	25		26
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	25	[1]	26	[2]
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	0		0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	0	[1]	0	[2]
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	0		0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Fair Value of Plan Assets	$ 0	[1]	$ 0	[2]
International Equity [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	7.00%		7.00%
Fixed Income Funds [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	70.00%		70.00%
U.S. Equity [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	23.00%		23.00%
Benefit Obligation [Member]
Postemployment Benefits
Deferred Compensation Liability, Classified, Noncurrent	$ 3		$ 3

[1] 70% of the amount invested in mutual funds was in fixed income securities; 23% was in U.S. equities and 7% was in international equities.

[2] 70% of the amount invested in mutual funds was in fixed income securities; 23% was in U.S. equities and 7% was in international equities.