Share-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
LTIP 2008 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent Of Share Based Award Available For Grant In Succeeding Calendar Year	2.00%
Percent Of Share Based Award Available For Grant Limit On Increase	3.00%
Number of unused share-based awards carried forward	279,000,000
2014 Plan RSU Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of unused share-based awards carried forward	10,000,000
Stock activity rollforward
RSU award issuable period	immediately, five years from grant, or at the time of the Director’s separation
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 1	one-third
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 2	one-third
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 3	one-third
Share Based Compensation Arrangement By Share Based Payment Award Requisite Performance Period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Stock activity rollforward
Outstanding, beginning of year (in shares)	20,300,000
Granted (in shares)	10,800,000
Vested (in shares)	(7,500,000)
Forfeited (in shares)	(200,000)
Outstanding, end of year (in shares)	23,400,000	20,300,000
RSU-stock expected to vest (in shares)	23,000,000
Outstanding, beginning of year (weighted-average grant date fair value)	$ 13.11
Granted (weighted-average grant-date fair value)	$ 15.40
Vested (weighted-average grant-date fair value)	$ 13.60
Forfeited (weighted-average grant-date fair value)	$ 13.87
Outstanding, end of year (weighted-average grant date fair value)	$ 14.01	$ 13.11
Outstanding, end of year (Aggregate Intrinsic Value)	$ 362
RSU-stock expected to vest (Aggregate Intrinsic Value)	358
Fair Value Disclosures [Abstract]
Granted	166	138	102
Weighted average for multiple grant dates (per unit)	15.40	12.77	12.43
Vested	102	101	109
Intrinsic Value [Abstract]
Vested	116	119	329
Compensation cost [Abstract]
Compensation cost	95	81	62
Tax benefit from compensation expense	49	48	36
Unrealized compensation cost on non-vested stock	68
Unrealized compensation weighted average period non-vested stock	1 year 9 months 22 days
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 1	one-third
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 2	one-third
Share Based Compensation Arrangement by Share based Payment Award Vesting Rights Percentage Anniversary Year 3	one-third
Stock Option Expiration Period, from Date of Grant	10 years
Compensation cost [Abstract]
Compensation cost	27	18	26
Tax benefit from compensation expense	9	11	16
Unrealized compensation cost on non-vested stock	14
Unrealized compensation weighted average period non-vested stock	1 year 6 months
Stock Option Activity [Abstract]
Outstanding, beginning of year (in shares)	79,100,000	108,000,000
Granted (in shares)	6,300,000	5,900,000
Exercised (in shares)	(19,900,000)	(33,100,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period	(1,600,000)	(1,600,000)
Forfeited (in shares)	(100,000)	(100,000)
Outstanding, end of year (in shares)	63,800,000	79,100,000	108,000,000
Exercisable, end of year (in shares)	51,500,000	67,600,000
Outstanding, beginning of year (weighted-average exercise price)	$ 9.17	$ 9.14
Granted (weighted-average exercise price)	$ 15.58	$ 12.76
Exercised (weighted-average exercise price)	$ 8.68	$ 9.76
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price	$ 13.39	$ 8.26
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	$ 15.16	$ 12.80
Outstanding, end of year (weighted-average exercise price)	$ 9.83	$ 9.17	$ 9.14
Exercisable, end of year (weighted-average exercise price)	$ 8.81	$ 8.53
Stock option plans, exercise price, lower range	$ 1.96	$ 1.96
Stock option plans, exercise price, upper range	$ 16.43	$ 16.49
Fair Value [Abstract]
Fair value of vested options	34	41	37
Vested (in shares)	51,500,000
Vested weighted average exercise price (dollars per share)	8.81
Average remaining term	3 years 6 months
Stock options expected to vest	12,100,000
Weighted average exercise price expected to vest (dollars per share)	14.13
Average remaining term after forfeitures	8 years 6 months
Intrinsic Value of Stock Options [Abstract]
Intrinsic value of vested options	344
Intrinsic value of unvested options (after forfeitures)	18
Cash received from exercise of stock options	173
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options	10
New stock issuances to settle exercised options	324
Difference between fair value and shares issued	$ 151	$ 188	$ 44
Nonvested Options Roll Forward [Abstract]
Non-vested, beginning of year (in shares)	11,500,000
Granted (in shares)	6,300,000
Vested (in shares)	(5,400,000)
Non-vested, end of year (in shares)	12,300,000	11,500,000
Non-vested, beginning of year (weighted-average grant-date fair value)	$ 5.78
Granted (weighted-average grant-date fair value)	$ 6.21	$ 5.03	$ 5.88
Vested (weighted-average grant-date fair value)	$ 6.28
Forfeited (weighted-average grant-date fair value)	$ 6.10
Non-vested, end of year (weighted-average grant-date fair value)	$ 5.78	$ 5.78
Assumptions [Abstract]
Annualized dividend yield	3.00%	3.00%	2.00%
Expected volatility	51.50%	52.20%	53.80%
Risk free interest rate	2.40%	1.50%	1.60%
Expected stock option term (in years)	7 years 9 months	7 years 8 months	7 years 2 months
Outstanding Options (in shares)	63,800,000
Exercisable Options (in shares)	51,500,000
Stock Option Plan Exercise Range 1 [Member] | Employee Stock Option [Member]
Assumptions [Abstract]
Outstanding Options (in shares)	9,000,000
Outstanding Options (weighted-average life (years))	4 years 2 months
Outstanding Options (weighted-average exercise price)	$ 2.29
Exercisable Options (in shares)	9,000,000
Exercisable Options (weighted-average exercise price)	$ 2.29
Stock Option Plan Exercise Range 2 [Member] | Employee Stock Option [Member]
Assumptions [Abstract]
Outstanding Options (in shares)	20,800,000
Outstanding Options (weighted-average life (years))	2 years 1 month
Outstanding Options (weighted-average exercise price)	$ 7.27
Exercisable Options (in shares)	20,800,000
Exercisable Options (weighted-average exercise price)	$ 7.27
Stock Option Plan Exercise Range 3 [Member] | Employee Stock Option [Member]
Assumptions [Abstract]
Outstanding Options (in shares)	23,600,000
Outstanding Options (weighted-average life (years))	5 years 1 month
Outstanding Options (weighted-average exercise price)	$ 12.60
Exercisable Options (in shares)	17,600,000
Exercisable Options (weighted-average exercise price)	$ 12.59
Stock Option Plan Exercise Range 4 [Member] | Employee Stock Option [Member]
Assumptions [Abstract]
Outstanding Options (in shares)	10,400,000
Outstanding Options (weighted-average life (years))	8 years 0 months
Outstanding Options (weighted-average exercise price)	$ 15.25
Exercisable Options (in shares)	4,100,000
Exercisable Options (weighted-average exercise price)	$ 14.76