STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2016

NOTE 2. STOCK-BASED COMPENSATION

Presented below is a summary of the stock-based compensation cost and associated tax benefit included in the accompanying consolidated statements of operations:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Stock-based compensation cost	$	23.5	$	21.7	$	48.9	$	44.4
Tax benefit	$	7.5	$	6.7	$	15.9	$	14.6

During the first six months of 2016, the Company granted 0.5 million employee stock options, which had a weighted average grant date fair value of $22.95 per share based on the Black-Scholes option-pricing model. The Company also granted 1.2 million shares of restricted stock in the first six months of 2016, which had a weighted average grant date fair value of $80.88 per share. Both the employee stock options and restricted stock generally vest ratably over a four-year period. Additionally, the Company granted approximately 0.2 million shares of performance-based awards whereby the number of shares that ultimately vest are based on the achievement of certain non-market based performance metrics of the Company over a three-year period. The weighted average grant date fair value of these awards was $76.50 per share.

The following weighted average assumptions were used in determining the fair value for options granted in 2016:

Expected dividend yield	1.83%
Expected stock volatility	32.3%
Risk-free interest rate	1.60%
Expected holding period	6.8 years
Grant date fair value	$22.95

Unrecognized compensation expense at June 30, 2016 was $13.0 million and $150.7 million for stock options and unvested restricted stock, respectively, which is expected to be recognized over a weighted average period of 1.4 years and 1.8 years, respectively. Additionally, there was $16.7 million of unrecognized compensation expense relating to the aforementioned non-market based performance-based awards, which is expected to be recognized over a weighted average period of 1.1 years.

The following tables summarize information relating to stock option exercises and restricted stock vesting:

	Six Months Ended
	June 30,
Exercise of stock options:	2016		2015
Proceeds from stock option exercises	$	33.4	$	51.9
Aggregate intrinsic value	$	21.0	$	49.9
Tax benefit realized upon exercise	$	7.4	$	17.9
Number of shares exercised		0.6		1.0

	Six Months Ended
	June 30,
Vesting of restricted stock:	2016		2015
Fair value of shares vested	$	90.6	$	110.8
Tax benefit realized upon vesting	$	29.6	$	35.6
Number of shares vested		1.0		1.1

	Six Months Ended
	June 30,
Vesting of performance-based restricted stock:	2016		2015
Fair value of shares vested	$	23.6	$	43.1
Tax benefit realized upon vesting	$	8.4	$	15.6
Number of shares vested		0.2		0.5