Employment Benefit Plans Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Significant Concentrations of Risk	three		three
Defined Benefit Plan, Actual Plan Asset Allocations	47.00%		43.00%
Accrued dividend and interest receivable, Less than	$ 1		$ 1
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,289	[1]	2,342	[2]
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,082	[1],[3]	2,196	[2],[4]
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	207	[1],[3]	146	[2],[4]
Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[1],[3]	0	[2],[4]
Pension Plan [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	28		30
Pension Plan [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	28	[3]	30	[4]
Pension Plan [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Registered investment companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	19		28
Pension Plan [Member] | Registered investment companies [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	19	[3]	28	[4]
Pension Plan [Member] | Registered investment companies [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Registered investment companies [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | US Government Agencies Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	12		13
Pension Plan [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	12	[3]	13	[4]
Pension Plan [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Collateralized Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	3		6
Pension Plan [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	3	[3]	6	[4]
Pension Plan [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
Pension Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	167		97
Pension Plan [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	3	[3]	0	[4]
Pension Plan [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	164	[3]	97	[4]
Pension Plan [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3]	0	[4]
UNITED STATES | Pension Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,001	[5]	2,091	[6]
UNITED STATES | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,001	[3],[5]	2,091	[4],[6]
UNITED STATES | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3],[5]	0	[4],[6]
UNITED STATES | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3],[5]	0	[4],[6]
International [Member] | Pension Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	59	[5]	77	[6]
International [Member] | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	59	[3],[5]	77	[4],[6]
International [Member] | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	[3],[5]	0	[4],[6]
International [Member] | Pension Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	$ 0	[3],[5]	$ 0	[4],[6]

[1] Excludes less than $1 million accrued for dividend and interest receivable.

[2] Excludes less than $1 million accrued for dividend and interest receivable.

[3] See Note 2 to the Consolidated Financial Statements under the heading “Fair Value Measurements” for a definition of each of these levels of inputs.

[4] See Note 2 to the Consolidated Financial Statements under the heading “Fair Value Measurements” for a definition of each of these levels of inputs.

[5] As of December 31, 2015, three equity securities each exceeded 10 percent of total plan assets. These investments represent approximately 47 percent of total plan assets.

[6] As of December 31, 2014, three equity securities each exceeded 10 percent of total plan assets. These investments represented approximately 43 percent of total plan assets.