Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2002	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Aug. 31, 1999
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation pre-tax unrecognized compensation cost		$ 134.7
Weighted average period for recognizing compensation cost, in years		1 year 2 months 12 days
Income tax benefits realized from exercise of stock options and vesting of stock units and deferred stock units		131.5	79.0	123.5
End of year stock price		$ 40.91
In the money options exercisable		3,800,000
Stock Based Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of stock options granted		$ 25.20	$ 14.93	$ 16.49
Total pre-tax intrinsic value of options exercised		47.9	22.6	67.5
Total fair value of vested options		16.6	14.8	14.6
Proceeds from stock options exercised		27.8	12.6	33.6
Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of equity instruments other than options granted		$ 29.17	$ 32.48	$ 39.95
Each DSU receives this number of shares of common stock upon vesting		1
Holder elect to defer vested shares period, minimum in years		1 year
Holder elect to defer vested shares period, maximum in years		10 years
The amount typically vested by anniversary grant date, percentage		50.00%
Equal installment percentage for remaining DSUs to be vested in two years from grant date		12.50%
Number of years from date of grant DSUs are fully vested		2 years
Director's minimum period of service before vesting accelerates, in years		1 year
Director's vesting before acceleration after departure, percentage		100.00%
Total pre-tax intrinsic value end of year		2.3	0.5	3.0
Total fair value of vested and distributed		2.4	0.5	1.4
Unvested Deferred Stock Units		70,738
Aggregate instrinsic value		2.9
Weighted average contractual remaining life, in years		6 years 2 months 9 days
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of equity instruments other than options granted		$ 35.82	$ 33.75	$ 26.56
Total pre-tax intrinsic value end of year		98.3	68.0	72.0
Total fair value of vested and distributed		71.4	44.7	47.2
Number of equity instruments other than options unnvested		5,900,000
Aggregate instrinsic value		196.0
Weighted average contractual remaining life, in years		5 years 8 months 12 days
Each RSU receives this number of shares of common stock upon vesting		1
Restricted stock unit vesting provision, minimum in years		3 years
Restricted stock unit vesting provision, maximum in years		4 years
Capitalized Internal Use Software [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional stock based compensation		7.7	7.3	7.5
1998 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock approved for issuance under plan		48,300,000
Exercise price of incentive stock options percentage of fair market value, minimum		100.00%
Exercise price of incentive stock options percentage of fair market value, minimum in certain cases		110.00%
Stock option vesting period, in years		4 years
Term of options granted, maximum period in years		10 years
Term of incentive options granted, maximum period, in years		5 years
Voting stock minimum percentage before applying incentive stock granted term limits		10.00%
2001 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock approved for issuance under plan		5,000,000
Stock option vesting period, in years		4 years
Term of options granted, maximum period in years		10 years
Term of incentive options granted, maximum period, in years		5 years
Voting stock minimum percentage before applying incentive stock granted term limits		10.00%
2006 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock approved for issuance under plan		7,500,000
Exercise price of incentive stock options percentage of fair market value, minimum		100.00%
Exercise price of incentive stock options percentage of fair market value, minimum in certain cases		110.00%
Stock option vesting period, in years		4 years
Term of options granted, maximum period in years		7 years
2009 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock approved for issuance under plan		15,500,000
Exercise price of incentive stock options percentage of fair market value, minimum		100.00%
Exercise price of incentive stock options percentage of fair market value, minimum in certain cases		110.00%
Stock option vesting period, in years		4 years
Term of options granted, maximum period in years		7 years
1999 ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock approved for issuance under plan					3,100,000
Maximum amount of shares available for issuance	1,500,000
Aggregate amount of shares available, maximum	20,000,000
Discount on fair market value for purchase of stock, percentage	15.00%
Issuance of common stock under employee stock purchase plan, shares		700,000	500,000	500,000
Weighted average purchase price		$ 24.76	$ 25.75	$ 25.62
Total cash proceeds from shares purchased		16.8	12.7	12.2
Amount withheld from employees for future purchases		$ 1.9
Weighted average fair value of equity instruments other than options granted		$ 8.71	$ 10.24	$ 9.86