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Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2012

Share-Based Compensation.

Schedule of transactions of the Company's stock options

		Stock Options			Weighted Average Exercise Price			Weighted Average Remaining Contractual Life (years)

Unexercised options outstanding—January 1, 2012			5.1		$	68.18
Options granted			0.1			121.90
Options exercised			(1.4	)		54.45
Options forfeited			0.0			85.72

Unexercised options outstanding—December 31, 2012			3.8			74.04			4.1

Exercisable at December 31, 2012			2.5			68.64			3.6

Schedule of assumptions used to determine fair value of options granted

		For the Years Ended December 31,

		2010			2011			2012
Dividend yield			0.0	%		0.0	%		0.0	%
Expected volatility⁽¹⁾			32.4	%		33.1	%		36.8	%
Risk-free interest rate⁽²⁾			1.6	%		1.3	%		0.7	%
Expected life of options (in years)⁽³⁾			4.5			4.8			5.0
Forfeiture rate⁽³⁾			4.8	%		2.4	%		1.4	%

(1): Based on historical and implied volatility.
(2): Based on the U.S. Treasury yield curve in effect at the date of grant.
(3): Based on the Company's historical data and expected exercise behavior.

Summary of transactions of the Company's restricted stock

		Restricted Stock			Weighted Average Grant Date Value

Units outstanding—January 1, 2012			0.4		$	52.66
Units granted			0.2			127.33
Units issued			(0.2	)		48.54
Units forfeited			(0.0	)		52.33

Units outstanding—December 31, 2012			0.4			84.53

Summary of recent share based compensation expense

Period		Share-Based Compensation Expense			Tax Benefit

2010		$	19.5		$	7.5
2011			30.3			11.6
2012			47.6			18.2