Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Summary Of Restricted Stock Activity

Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value Per Share
Non-vested as of December 31, 2016	168,546		$	111.91
Granted	8,543		200.79
Vested	(17,338	)	127.83
Forfeited	(451	)	198.81
Non-vested as of December 31, 2017	159,300		$	114.70

Summary Of Restricted Stock Units Activity

A summary of the restricted stock unit activity under the Incentive Plan for the year ended December 31, 2017, is presented below:

Restricted Stock Units	Number of Restricted Stock Units		Weighted Average Grant-Date Fair Value Per Share		Aggregate Intrinsic Value (2) (in millions)		Weighted Average Remaining Contractual Term (in years)
Outstanding as of December 31, 2016	455,823		$	101.75
Granted	108,100		206.45
Converted	(34,836	)	40.12
Forfeited	(6,260	)	178.07
Outstanding as of December 31, 2017 (1)	522,827		$	126.59	$	169.1	5.2
Vested as of December 31, 2017	258,195		$	106.67	$	83.5	4.2

(1) No RSUs outstanding at December 31, 2017 were convertible to shares of common stock.

(2) The intrinsic value of RSUs is measured by applying the closing stock price as of December 31, 2017 to the applicable number of units.

Schedule Of Stock Based Compensation Expense

Stock-based compensation expense consists of the following:

(In millions)	For the Years Ended December 31,
	2017		2016		2015
Restricted stock	$	2.9	$	2.8	$	3.2
Restricted stock units	12.5		4.6		9.2
Total	$	15.4	$	7.4	$	12.4

Schedule Of Future Share-Based Compensation Cost

over a weighted average period of 1.8 years, as follows:

(In millions)
For the Years Ended December 31,	Restricted Stock Units		Restricted Stock		Total Projected Expense
2018	$	8.0	$	2.1	$	10.1
2019	4.5		1.4		5.9
2020	2.2		1.1		3.3
2021	0.5		0.9		1.4
2022	0.1		0.8		0.9
Thereafter	—		1.7		1.7
Total	$	15.3	$	8.0	$	23.3