Equity Incentive Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity Incentive Plans
Compensation expense	$ 86,000,000	$ 64,000,000	$ 68,000,000
Share-based compensation arrangement by share-based payment award, recognized tax benefits	30,000,000	21,000,000	23,000,000
Cash received from the exercise of options	99,000,000	19,000,000	28,000,000
Tax benefit realized on options exercised and stock unrestricted	28,000,000	10,000,000	11,000,000
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	100,000,000
Tax (expense) benefit realized related to all stock-based compensation included in shareholder's equity	6,000,000	(400,000)	500,000
Common stock authorized for stock-based awards (in shares)	77,800,000
Common stock reserved for further issuance (in shares)	16,200,000
Stock options
Equity Incentive Plans
Tax (expense) benefit realized related to all stock-based compensation included in shareholder's equity	8,000,000	3,000,000	4,000,000
Vesting period of options granted prior to 2010	4 years
Portion of awards vesting and unrestricting on second anniversary of grant date (as a percent)	50.00%
Portion of awards vesting and unrestricting on third and fourth anniversaries of grant date (as a percent)	25.00%
Expiration term for options	10 years
Age for normal retirement	60 years
Requisite service period for normal retirement	5 years
Age for early retirement	55 years
Requisite service period for early retirement	10 years
Vesting period of options	12 months
Period for exercise of option	3 months
Assumptions used to determine fair value of options granted
Weighted average expected term	9 years	7 years 10 months 24 days	7 years 9 months 18 days
Expected volatility, low end of the range (as a percent)	20.20%	22.10%	23.70%
Expected volatility, high end of the range (as a percent)	53.90%	53.90%	52.30%
Weighted average volatility (as a percent)	34.60%	35.10%	35.10%
Expected dividends, minimum range (as a percent)	2.20%	2.50%	2.40%
Expected dividends, maximum range (as a percent)	3.00%	3.70%	2.80%
Weighted average expected dividends (as a percent)	2.80%	2.70%	2.60%
Risk-free rate, low end of the range (as a percent)	0.00%	0.00%	0.10%
Risk-free rate, high end of the range (as a percent)	2.20%	3.50%	3.90%
Stock option activity
Outstanding at the beginning of the period (in shares)	33,947,000
Granted (in shares)	3,727,000
Exercised (in shares)	(4,113,000)
Forfeited (in shares)	(619,000)
Expired (in shares)	(3,299,000)
Outstanding at the end of the period (in shares)	29,643,000	33,947,000
Outstanding, net of expected forfeitures (in shares)	29,371,000
Outstanding, exercisable ("vested") (in shares)	18,840,000
Outstanding at the beginning of the period (in dollars per share)	$ 39.00
Granted (in dollars per share)	$ 31.62
Exercised (in dollars per share)	$ 24.00
Forfeited (in dollars per share)	$ 29.86
Expired (in dollars per share)	$ 43.81
Outstanding at the end of the period (in dollars per share)	$ 39.81	$ 39.00
Outstanding, net of expected forfeitures (in dollars per share)	$ 39.89
Outstanding, exercisable ("vested") (in dollars per share)	$ 46.07
Aggregate intrinsic value, Outstanding	193,556,000
Aggregate intrinsic value, net of expected forfeitures, outstanding	191,143,000
Aggregate intrinsic value, exercisable ("vested"), outstanding	71,729,000
Weighted average remaining contractual term, Outstanding	5 years 1 month 6 days
Weighted average remaining contractual term, net of expected forfeitures, outstanding	5 years 1 month 6 days
"Weighted average remaining contractual term, exercisable (""vested""), outstanding	3 years 6 months
Weighted average grant date fair value of options granted (in dollars per share)	$ 8.69	$ 9.49	$ 9.89
Intrinsic value of options exercised	52,000,000	15,000,000	16,000,000
Nonqualified stock options
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	43,000,000
Expected period of recognition of unrecognized compensation cost	2 years 1 month 24 days
Restricted stock units
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	46,000,000
Expected period of recognition of unrecognized compensation cost	2 years 2 months 19 days
Portion of awards vesting and unrestricting on second anniversary of grant date (as a percent)	50.00%
Portion of awards vesting and unrestricting on third and fourth anniversaries of grant date (as a percent)	25.00%
Vesting period of options	12 months
Stock units activity
Outstanding at the beginning of the period (in shares)	4,326,000
Granted (in shares)	1,253,000
Vested (in shares)	(939,000)
Forfeited (in shares)	(188,000)
Outstanding at the end of the period (in shares)	4,452,000	4,326,000
Weighted average grant date fair value, nonvested at the beginning of the period (in dollars per share)	$ 28.76
Weighted average grant date fair value, granted (in dollars per share)	$ 31.89	$ 31.38	$ 31.32
Weighted average grant date fair value, vested (in dollars per share)	$ 40.13
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.15
Weighted average grant date fair value, nonvested at the end of the period (in dollars per share)	$ 27.27	$ 28.76
Total fair value of restricted stock and restricted stock units vested	30,000,000	13,000,000	16,000,000
Performance stock awards
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	$ 11,000,000
Expected period of recognition of unrecognized compensation cost	1 year 10 months 28 days
Stock units activity
Granted (in shares)	460,000
Forfeited (in shares)	(23,000)
Outstanding at the end of the period (in shares)	437,000
Weighted average grant date fair value, granted (in dollars per share)	$ 31.41
Weighted average grant date fair value, forfeited (in dollars per share)	$ 31.00
Weighted average grant date fair value, nonvested at the end of the period (in dollars per share)	$ 31.43