Employee Benefit Plans Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	$ 88		$ 110		$ 115
Postemployment Benefits [Abstract]
Postemployment Benefits, Period Credit			1
Postemployment Benefits, Period Expense	3				1
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Benefit expense related to deferred compensation plans	1		1		$ 1
Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	$ 88	[1]	110	[2]
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	13.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	23.00%
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	3.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	13.00%
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	69.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	79.00%
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%
Fair Value, Inputs, Level 1 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	$ 88		110
Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	88	[1]	110	[2]
Fair Value, Inputs, Level 2 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0		0
Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0	[1]	0	[2]
Fair Value, Inputs, Level 3 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0		0
Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0	[1]	$ 0	[2]
Other Postretirement Benefit Plans, Defined Benefit [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Defined Benefit Plan, Estimated future contributions in the next fiscal year	9
Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Postretirement benefit payments - 2017	11
Postretirement benefit payments - 2018	12
Postretirement benefit payments - 2019	13
Postretirement benefit payments - 2020	15
Postretirement benefit payments - 2021	16
Postretirement benefit payments - 2022-2026	$ 90
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	8.00%		8.00%
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	73.00%		73.00%
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	19.00%		19.00%
Benefit Obligation [Member]
Postemployment Benefits [Abstract]
Postemployment benefit obligations	$ 6		$ 6
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Other non-qualified plans benefit obligations deferred compensation	$ 11		$ 11

[1] 73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.

[2] 73% of the amount invested in mutual funds was in fixed income securities; 19% was in U.S. equities and 8% was in international equities.