Share-based compensation plans (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [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 June 30,					Six Months Ended June 30,
(in millions)	2020			2019		2020			2019
Performance share units	$	2.4		8.8		$	7.0		14.6
Restricted stock units	1.7			1.9		3.0			3.9
Deferred stock units and fees paid in stock	0.3			0.3		0.6			0.6
Performance-based stock options	0.5			5.4		1.2			6.5
Time-based vesting stock options	0.5			0.3		0.8			0.5
Cash based awards	0.4			—		0.4			—
Share-based payment expense	5.8			16.7		13.0			26.1
Income tax benefit	(1.2		)	(3.8	)	(2.8		)	(6.0	)
Share-based payment expense, net of tax	$	4.6		12.9		$	10.2		20.1

Option activity

The following table summarizes performance-based stock option activity during the first six months of 2020: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2019	1,191.1	$	11.52
Granted	—	—
Forfeited	—	—
Exercised	—	—
Outstanding balance as of June 30, 2020	1,191.1	$	11.52

The following table summarizes time-based stock option activity during the first six months of 2020: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2019	127.0	$	21.56
Granted	80.8	21.10
Forfeited	—	—
Exercised	—	—
Outstanding balance as of June 30, 2020	207.8	$	21.38

Nonvested share activity

The following table summarizes RSU activity during the first six months of 2020: 

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2019	172.7		$	71.87
Granted	83.1		75.41
Forfeited	(10.0	)	78.68
Conversion to cash settled awards(a)	(1.3	)	72.80
Vested	(83.3	)	67.31
Nonvested balance as of June 30, 2020	161.2		$	75.63

(a) Certain RSUs were modified in the first quarter of 2020 to change the awards' classification from share-settled to cash-settled. The weighted-average grant date fair value per share shown above is the removal of the original fair value.

The following table summarizes all PSU activity during the first six months of 2020:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2019	564.2		$	70.10
Granted	242.7		84.60
Forfeited	(16.9	)	75.92
Conversion to cash settled awards(a)	(4.6	)	65.42
Vested(b)	(204.3	)	56.72
Nonvested balance as of June 30, 2020	581.1		$	80.73

(a) Certain IM PSUs were modified in the first quarter of 2020 to change the awards' classification from share-settled to cash-settled. The weighted-average grant date fair value per share shown above is the removal of the original fair value.

(b)

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, 2019 were 394.0 thousand, compared to target shares of 204.3 thousand.

The following table summarizes all DSU activity during the first six months of 2020:

	Shares (in thousands)		Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2019	12.1		$	79.69
Granted	21.6		40.46
Vested	(11.1	)	78.70
Nonvested balance as of June 30, 2020	22.6		$	42.70