Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock-Based Compensation Expense by Type of Award

The following table details the stock-based compensation expense by type of award for the years ended December 31, 2015, 2014 and 2013:

	Year Ended December 31,
(In millions, except per share data)	2015		2014		2013
Non-qualified stock options	$	3.3	$	3.6	$	3.8
Restricted stock, service based (“RSUs”)		6.4		6.0		6.0
Restricted stock, performance based (“PRSUs”)		7.9		7.4		8.8
Employee stock purchase plan		0.3		0.2		0.3
Stock-based compensation expense	$	17.9	$	17.2	$	18.9
Tax benefit from stock options exercised during the period	$	9.2	$	5.8	$	5.3

Summary of Option Activity

A summary of option activity under the plan for the three years ended December 31, 2015 is as follows:

	Number of Options (In millions)			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (in years)
Outstanding at December 31, 2012		3.3		$	15.67		6.26
Options granted		0.3		$	28.27
Options exercised		(0.6	)	$	10.41
Outstanding at December 31, 2013		3.0		$	17.30		5.96
Options granted		0.2		$	43.01
Options exercised		(0.4	)	$	14.66
Outstanding at December 31, 2014		2.8		$	19.12		4.95
Options granted		0.2		$	43.96
Options exercised		(0.7	)	$	12.77
Outstanding at December 31, 2015		2.3		$	23.75		5.39

Schedule of Other Stock Option Statistics

	Year Ended December 31,
(In millions, except weighted average exercise price)	2015		2014
Aggregate intrinsic value of outstanding options	$	51.7	$	63.6
Aggregate intrinsic value of exercisable options	$	48.7	$	59.5
Total intrinsic value of options exercised	$	26.0	$	9.7
Total number of options exercisable		1.8		2.3
Weighted average exercise price of options exercisable	$	19.83	$	16.16
Total unrecognized compensation cost on nonvested options (a)	$	1.2	$	1.1

(a) Unrecognized compensation cost relates to nonvested stock options and is expected to be recognized over the remaining vesting period ranging from one year to three years.

Summary of Information about Outstanding and Exercisable Stock Options

The following table summarizes information about non-qualified stock options outstanding as of December 31, 2015:

		Options Outstanding							Options Exercisable
Range of Exercise Prices			Number of Options Outstanding (a)		Weighted Average Remaining Life (in Years)		Weighted Average Exercise Price			Number of Options Exercisable (a)		Weighted Average Exercise Price
$	7.83 – 19.02			1.0		3.78	$	14.75			1.0	$	14.75
$	20.76 – 28.27			0.9		5.82	$	25.42			0.7	$	25.02
$	43.01 – 43.96			0.4		8.66	$	43.57			0.1	$	43.01
$	7.83 – 43.96			2.3		5.39	$	23.75			1.8	$	19.83

(a) in millions

Schedule of Assumptions Used in Determining the Estimated the Fair Value of Stock Options

We estimated the fair value of stock options at the grant date using the Black-Scholes option pricing model with the following assumptions for the years ended December 31, 2015, 2014 and 2013:

	2015			2014			2013
Risk-free interest rate		1.56	%		2.17	%		1.08	%
Expected option life (in years) Executive		6.84			6.88			6.32
Expected option life (in years) Non-Executive		6.09			6.18			4.80
Dividend yield		1.0	%		—	%		—	%
Volatility		35.59	%		37.52	%		40.12	%
Weighted-average fair value per option granted	$	14.95		$	17.91		$	11.07

Summary of the Company's Service Based RSU Activity

The table presented below provides a summary of the Company’s RSU activity for the years ended December 31, 2015, 2014 and 2013:

	Number of RSUs (In millions)			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2012		0.8		$	18.90
RSUs granted		0.2		$	28.95
RSUs issued		(0.4	)	$	15.70
Outstanding at December 31, 2013		0.6		$	23.79
RSUs granted		0.1		$	42.76
RSUs issued		(0.2	)	$	24.13
Outstanding at December 31, 2014		0.5		$	27.76
RSUs granted		0.1		$	43.96
RSUs issued		(0.1	)	$	28.95
Outstanding at December 31, 2015		0.5		$	31.73

Summary of the Company's PRSU Activity

The table presented below provides a summary, of the Company’s PRSU activity, at original grant amounts, for the years ended December 31, 2015, 2014 and 2013:

	Number of PRSUs (In millions)			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2012		0.5		$	16.93
PRSUs granted		0.2		$	28.27
PRSUs additional performance shares		0.3		$	10.72
PRSUs issued		(0.5	)	$	10.64
Outstanding at December 31, 2013		0.5		$	24.60
PRSUs granted		0.1		$	43.01
PRSUs additional performance shares		0.1		$	19.02
PRSUs issued		(0.3	)	$	19.01
Outstanding at December 31, 2014		0.4		$	31.68
PRSUs granted		0.1		$	43.96
PRSUs additional performance shares		0.1		$	42.23
PRSUs issued		(0.2	)	$	24.95
Outstanding at December 31, 2015		0.4		$	36.59