Share-Based Compensation

6 Months Ended

Jun. 30, 2017

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

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



	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2016		2017		2016		2017
Share-based compensation	$	10.8	$	10.3	$	20.0	$	19.7
Tax benefit	4.2		4.0		7.7		7.6

The Company has $66.4 million and $83.4 million of unrecognized share-based compensation as of December 31, 2016 and June 30, 2017, respectively, which will be recognized over a weighted average period of approximately three years (assuming no forfeitures).

Stock Options

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



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)
Unexercised options outstanding - December 31, 2016	1.4		$	108.53
Options granted	0.0		152.36
Options exercised	(0.6	)	96.52
Options forfeited	0.0		140.26
Unexercised options outstanding - June 30, 2017	0.8		116.71		3.6
Exercisable at June 30, 2017	0.4		107.81		1.6

For the six months ended June 30, 2016 and 2017, the Company granted stock options with fair values of $16.0 million and $0.4 million, respectively. Stock options generally vest over a period of three to four years and expire seven years after the grant date. All options have been granted with exercise prices equal to the closing price of the Company’s common stock on the grant date. In certain circumstances, option awards also require certain performance conditions to be satisfied in order for the options to be exercised.

The fair value of options granted was estimated using the Black-Scholes option pricing model. For the six months ended June 30, 2016 and 2017, the weighted average fair value of options granted was $38.90 and $46.49, per option, respectively, based on the weighted-average grant date assumptions stated below.



	For the Six Months Ended June 30,
	2016		2017
Dividend yield	—	%	0.5	%
Expected volatility	30.6	%	30.1	%
Risk-free interest rate	1.6	%	2.2	%
Expected life of options (in years)	5.7		5.7
Forfeiture rate	—	%	—	%

Restricted Stock

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



	Restricted Stock Units		Weighted Average Grant Date Value
Unvested units - December 31, 2016	0.6		$	168.84
Units granted	0.2		152.89
Units vested	(0.2	)	167.72
Units forfeited	(0.0	)	170.52
Unvested units - June 30, 2017	0.6		162.92

For the six months ended June 30, 2016 and 2017, the Company granted awards with fair values of $27.7 million and $36.4 million, respectively. These awards were valued based on the closing price of the Company’s common stock on the grant date and contain vesting conditions requiring service over a period of three to four years. In certain circumstances, awards also require certain performance conditions to be satisfied.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

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