Stock-Based Compensation

9 Months Ended

Sep. 30, 2015

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

The following table summarizes our stock-based compensation expense for the three and nine months ended September 30, 2015 and 2014.



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
(in millions)	2015			2014			2015			2014
Restricted stock units (“RSUs”) and performance-based RSUs (“PRSUs”)	$	3.6		$	4.7		$	11.5		$	9.0
Stock options	0.1			1.5			0.2			1.9
Stock-based compensation expense, before income taxes	3.7			6.2			11.7			10.9
Tax benefit	(0.3		)	(0.7		)	(1.0		)	(2.8		)
Stock-based compensation expense, net of tax	$	3.4		$	5.5		$	10.7		$	8.1

As of September 30, 2015, total unrecognized compensation cost related to non-vested RSUs and PRSUs was $24.1 million, which is expected to be recognized over a weighted average period of 2.2 years, and total unrecognized compensation cost related to non-vested stock options was $0.4 million, which is expected to be recognized over a weighted average period of 1.9 years.

RSUs and PRSUs

The following table summarizes activity for the nine months ended September 30, 2015, of RSUs and PRSUs issued to our employees.



	Activity		Weighted Average Per Share Grant Date Fair Market Value
Non-vested as of December 31, 2014	1,278,602		$	21.92
Granted:
RSUs	419,609		29.64
PRSUs	226,197		29.83
Vested:
RSUs	(468,765	)	21.28
PRSUs	(75,460	)	28.61
Forfeitures:
RSUs	(31,744	)	25.41
PRSUs	(25,751	)	26.42
Non-vested as of September 30, 2015	1,322,688		26.46

Stock Options

The following table summarizes activity for the nine months ended September 30, 2015, of stock options issued to our employees.



	Activity		Weighted Average Exercise Price
Outstanding as of December 31, 2014	450,890		$	15.29
Exercised	(141,600	)	14.67
Forfeited or expired	(14,393	)	12.73
Outstanding as of September 30, 2015	294,897		15.72

Exercisable as of September 30, 2015	208,515		12.77