Share-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The following is a summary of share-based compensation expense:



	For the Three Months Ended March 31,
	2015		2016
Share-based compensation	$	8.0	$	9.2
Tax benefit	3.1		3.6

Schedule of Company Stock Option Transactions

The following table summarizes the transactions of the Company’s stock options:



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)
Unexercised options outstanding - December 31, 2015	1.4		$	96.18
Options granted	0.4		122.40
Options exercised	(0.1	)	80.32
Unexercised options outstanding - March 31, 2016	1.7		103.09		3.1
Exercisable at March 31, 2016	1.3		95.19		1.9

Schedule of Fair Value of Options Granted and Assumptions

The weighted average fair value of options granted during the three months ended March 31, 2015 and 2016 was $53.59 and $38.90 per option, respectively, based on the weighted-average grant date assumptions stated below.



	For the Three Months Ended March 31,
	2015		2016
Dividend yield	—	%	—	%
Expected volatility⁽¹⁾	27.9	%	30.6	%
Risk-free interest rate⁽²⁾	1.4	%	1.6	%
Expected life of options (in years)⁽³⁾	5.0		5.7
Forfeiture rate	—	%	—	%

___________________________


⁽¹⁾	Expected volatility is based on historical and implied volatility.


⁽²⁾	Risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date of the grant.


⁽³⁾	Expected life of options (in years) is based on the Company’s historical data and expected exercise behavior.

Schedule of Company Restricted Stock Unit Transactions

The following table summarizes the transactions of the Company’s restricted stock units:



	Restricted Stock Units		Weighted Average Grant Date Value
Unvested units - December 31, 2015	0.6		$	192.04
Units granted	0.2		122.43
Units vested	(0.2	)	181.00
Units forfeited	(0.0)		197.79
Unvested units - March 31, 2016	0.6		169.57