Share-based compensation plans (Tables)

9 Months Ended

Sep. 30, 2019

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

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

Compensation expenses for the share-based awards were as follows:

	Compensation Expense					Compensation Expense
	Three Months Ended September 30,					Nine Months Ended September 30,
(in millions)	2019			2018		2019			2018
Performance Share Units	$	7.0		3.1		$	21.6		9.7
Market Share Units	—			—		—			0.1
Restricted Stock Units	1.4			1.6		5.3			4.9
Deferred Stock Units and fees paid in stock	0.3			0.4		0.9			0.9
Stock Options	1.1			1.2		8.1			3.2
Share-based payment expense	9.8			6.3		35.9			18.8
Income tax benefit	(2.3		)	(1.5	)	(8.3		)	(4.4	)
Share-based payment expense, net of tax	$	7.5		4.8		$	27.6		14.4

Option activity

The following table summarizes performance-based stock option activity during the first nine months of 2019: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2018	1,287.0	$	10.88
Granted	—	—
Forfeited	—	—
Exercised	—	—
Outstanding balance as of September 30, 2019(a)	1,287.0	$	14.00

(a) Certain performance-based stock options were modified in the second quarter of 2019. The weighted-average grant date fair value per share at September 30, 2019 reflects the inclusion of the modified fair value per share for the modified awards.

The following table summarizes time-based stock option activity during the first nine months of 2019: 

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2018	2.7		$	21.09
Granted	138.7		21.58
Forfeited	(14.4	)	21.60
Exercised	—		—
Outstanding balance as of September 30, 2019	127.0		$	21.56

Nonvested share activity

The following table summarizes all DSU activity during the first nine months of 2019:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2018	12.5		$	74.43
Granted	12.1		79.69
Vested	(12.5	)	74.43
Nonvested balance as of September 30, 2019	12.1		$	79.69

The following table summarizes all PSU activity during the first nine months of 2019:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2018	697.3		$	47.74
Granted	202.9		81.42
Forfeited	(19.2	)	72.64
Vested(a)(b)(c)	(316.1	)	32.35
Nonvested balance as of September 30, 2019(c)	564.9		$	70.01

(a) The vested PSUs presented are based on the target amount of the award. In accordance with the terms of the underlying award agreements, the actual shares earned and distributed for the performance period ended December 31, 2018 were 225.9 compared to target shares of 187.0. Additionally, in accordance with the terms of the underlying award agreements, the actual shares earned and distributed for the performance period ended June 30, 2017 were 129.1 compared to target shares of 129.1.

(b) Certain PSUs were modified and distributed in the first quarter of 2019 and the resulting impact was not material. 

(c) Certain PSUs were modified in the second quarter of 2019. A portion of these modified PSUs were distributed in the third quarter of 2019. The weighted-average grant date fair value per share at September 30, 2019 reflects the inclusion of the modified fair value per share for the remaining modified awards.

The following table summarizes RSU activity during the first nine months of 2019: 

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2018	235.8		$	52.63
Granted	92.2		78.08
Forfeited	(9.9	)	71.65
Vested	(133.8	)	42.92
Nonvested balance as of September 30, 2019(a)	184.3		$	71.74

(a) Certain RSUs were modified in the second quarter of 2019. The weighted-average grant date fair value per share at September 30, 2019 reflects the inclusion of the modified fair value per share for the modified awards.