Share-based compensation plans (Tables)

3 Months Ended

Mar. 31, 2017

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

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award

The following table summarizes all DSU activity during the first three months of 2017:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2016	29.7		$	29.41
Granted	—		—
Forfeited	(3.7	)	29.35
Vested	—		—
Nonvested balance as of March 31, 2017	26.0		$	29.42

The following table summarizes all PSU activity during the first three months of 2017:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2016	603.2		$	28.02
Granted	214.1		53.66
Forfeited	(12.1	)	27.53
Vested(a)	(134.3	)	24.39
Nonvested balance as of March 31, 2017	670.9		$	36.94

(a) The vested PSUs presented are based on the target amount of the award. In accordance with the terms of the underlying award agreements or plan provisions, the actual shares earned and distributed for the performance period ended December 31, 2016 were 252.0

The following table summarizes RSU activity during the first three months of 2017: 

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2016	296.5		$	27.84
Granted	91.7		51.96
Forfeited	(10.8	)	27.31
Vested	(88.6	)	27.47
Nonvested balance as of March 31, 2017	288.8		$	35.63

The following table summarizes all MSU activity during the first three months of 2017: 

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2016	141.7		$	27.02
Granted	—		—
Forfeited	—		—
Vested(a)	(67.5	)	23.34
Nonvested balance as of March 31, 2017	74.2		$	30.37

(a) The vested MSUs presented are based on the target amount of the award. In accordance with the terms of the underlying award agreements or plan provisions, the actual shares earned and distributed for the performance period ended December 31, 2016 were 81.8. No additional compensation expense was required to be recognized for the additional shares distributed, as the market condition was included in the $23.34 grant date fair value.

Compensation expenses are classified as selling, general and administrative expenses in the condensed consolidated statements of operations. Compensation expenses for the share-based awards were as follows:

	Compensation Expense
	Three Months Ended March 31,
(in millions)	2017			2016
Performance Share Units	$	2.6		1.3
Market Share Units	0.1			0.2
Restricted Stock Units	1.2			1.1
Deferred Stock Units	0.2			0.2
Stock Options	0.4			—
Share-based payment expense	4.5			2.8
Income tax benefit	(1.6		)	(1.0	)
Share-based payment expense, net of tax	$	2.9		1.8

Schedule of Share-based Compensation, Stock Options, Activity

The following table summarizes performance-based stock option activity during the first three months of 2017: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2016	580.9	$	6.01
Granted	298.9	11.97
Forfeited	—	—
Exercised	—	—
Outstanding balance as of March 31, 2017	879.8	$	8.04