Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

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

	Three Months Ended June 30,						Six Months Ended June 30,
(in millions)	2018			2017			2018			2017
Stock-based compensation expense	$	4.6		$	4.1		$	7.6		$	7.3
Tax benefit		(1.0	)		(1.4	)		(1.6	)		(2.5	)
Stock-based compensation expense, net of taxes	$	3.6		$	2.7		$	6.0		$	4.8

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

	Six Months Ended June 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		294,603			110.68		460,610			90.85
Exercised		(149,043	)		71.74		(180,940	)		59.50
Forfeited or cancelled		(50,491	)		88.48		(16,567	)		80.40
Outstanding, end of period		1,157,246			84.40		1,659,255			75.68

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

	Six Months Ended June 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		143,565			111.21		128,235			90.51
Vested		(71,556	)		72.56		(70,590	)		59.29
Forfeited		(16,890	)		89.89		(13,830	)		84.30
Outstanding, end of period		353,647			96.61		312,878			83.55
Performance-based and market-based restricted stock units:
Outstanding, beginning of period		102,586		$	81.21		115,057		$	78.82
Granted		34,280			117.65		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		115,209			93.34		155,336			81.19