Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Compensation cost for the Company’s stock-based awards and the related tax benefits were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
(in millions)	2018			2017			2018			2017
Stock-based compensation expense	$	4.0		$	3.7		$	10.6		$	10.2
Tax benefit		(0.8	)		(1.3	)		(2.2	)		(3.6	)
Stock-based compensation expense, net of taxes	$	3.2		$	2.4		$	8.4		$	6.6

Information on the Company’s stock option activity for the nine months ended September 30, 2018 and 2017 is summarized below.

	Nine Months Ended September 30,
	2018					2017
(in whole shares and dollars)	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, beginning of period		1,062,177		$	75.53		1,396,152		$	68.63
Granted		301,152			110.98		460,610			90.85
Exercised		(169,196	)		70.94		(327,205	)		57.29
Forfeited or cancelled		(54,063	)		89.09		(28,042	)		79.40
Outstanding, end of period		1,140,070			84.93		1,501,515			77.72

The following tables summarize activity information about employee restricted stock units:

	Nine Months Ended September 30,
	2018					2017
(in whole shares and dollars)	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Time-based restricted stock units:
Outstanding, beginning of period		298,528		$	83.45		269,063		$	73.91
Granted		148,619			111.67		128,850			90.53
Vested		(72,546	)		72.62		(70,590	)		59.29
Forfeited		(23,130	)		91.20		(26,615	)		84.59
Outstanding, end of period		351,471			97.10		300,708			83.52
Performance-based and market-based restricted stock units:
Outstanding, beginning of period		102,586		$	81.21		115,057		$	78.82
Granted		35,063			118.60		60,101			79.48
Vested		(14,032	)		70.24		(17,642	)		58.16
Forfeited		(7,625	)		81.91		(2,180	)		95.36
Outstanding, end of period		115,992			93.79		155,336			81.19