STOCK BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation Expense Resulting from Stock Option Awards, RSUs, PSUs and ESPP

The following table presents the total stock-based compensation expense resulting from stock option awards, restricted stock units (“RSUs”), performance-based restricted stock units (“PSUs”), and the Employee Stock Purchase Plan (“ESPP”) included in the Condensed Consolidated Statements of Income:

In millions
	Three Months Ended March 31,
	2018		2017
Selling, general and administrative - stock option plan	$	3.0	$	4.1
Selling, general and administrative - RSUs		2.1		1.4
Selling, general and administrative - PSUs		1.6		0.2
Selling, general and administrative - ESPP		0.4		0.3
Total pre-tax expense	$	7.1	$	6.0

Stock Option Activity

Stock option activity for the three months ended March 31, 2018 is summarized as follows:

	Number of Options			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life		Total Aggregate Intrinsic Value
						(in years)		(in millions)
Outstanding at January 1, 2018		5,393,417		$	96.91
Granted		338,834			62.13
Exercised		(38,203	)		53.63
Forfeited		(71,348	)		109.61
Canceled or expired		(101,631	)		102.66
Outstanding as of March 31, 2018		5,521,069		$	94.81		4.54	$	5.5
Exercisable as of March 31, 2018		3,951,661		$	93.48		3.87	$	5.5

Assumptions Used in Black-Scholes Option Pricing Model

The estimated fair value of stock options at the time of the grant using the Black-Scholes option pricing model was as follows:

	Three Months Ended March 31,
	2018			2017
Stock options granted (shares)		338,834			425,599
Weighted average fair value at grant date	$	16.87		$	19.53
Assumptions:
Expected term (in years)		4.89			4.82
Expected volatility		25.33	%		22.66	%
Expected dividend yield		—	%		—	%
Risk free interest rate		2.57	%		1.91	%

Summary of RSU Activity

A summary of the status of our non-vested RSUs and changes during the three months ended March 31, 2018, are as follows:

	Number of Units			Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Life		Total Aggregate Intrinsic Value
						(in years)		(in millions)
Non-vested at January 1, 2018		267,297		$	89.74
Granted		247,570			62.14
Vested and Released		(51,302	)		89.31
Forfeited		(10,395	)		90.32
Non-vested as of March 31, 2018		453,170		$	74.43		2.53	$	26.5

Summary of PSU Activity

A summary of the status of our non-vested PSUs and changes during the three months ended March 31, 2018, are as follows:

	Number of Units			Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Life		Total Aggregate Intrinsic Value
						(in years)		(in millions)
Non-vested at January 1, 2018		33,447		$	82.85
Granted		399,658			62.09
Vested and Released		-			-
Forfeited		(12,880	)		82.92
Non-vested as of March 31, 2018		420,225		$	63.11		2.32	$	24.6