Stock Based Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Option Activity

The following table provides a summary of option activity:

						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
				Exercise		Contractual		Intrinsic
	Options			Price		Term		Value
Outstanding at December 31, 2017		16.1		$	33.11
Granted		1.9			50.22
Exercised		(2.5	)		23.40
Cancelled		(0.1	)		48.55
Outstanding at September 30, 2018		15.4		$	36.60		5.6	$	351.1
Exercisable at September 30, 2018		9.5		$	29.16		4.1	$	288.0

Information Regarding Intrinsic Value of Stock Options Exercised and Stock Compensation Expense Related to Stock Option Awards

The following table provides information regarding the intrinsic value of stock options exercised and stock compensation expense related to stock option awards:  

	Three Months Ended				Nine Months Ended
	September 30,		September 30,		September 30,		September 30,
	2018		2017		2018		2017
Intrinsic Value of Stock Options Exercised	$	26.8	$	11.3	$	72.0	$	46.0
Stock Compensation Expense Related to Stock Option Awards	$	3.7	$	2.3	$	18.7	$	13.0
Issued Stock Options	0.0			0.3		1.9		2.1
Weighted Average Fair Value of Stock Options issued (per share)	$	0.0	$	38.02	$	9.63	$	13.12
Fair Value of Stock Options Issued	$	0.0	$	9.6	$	18.1	$	27.0

Assumptions Used in Valuation of Issued Stock Options

The following table provides a summary of the assumptions used in the valuation of issued stock options:

	Three Months Ended				Nine Months Ended
	September 30,	September 30,			September 30,			September 30,
	2018	2017			2018			2017
Risk-free interest rate	-		1.7	%		2.9	%		2.0	%
Expected life in years	-		4.4			7.3			6.9
Expected volatility	-		15.5	%		17.1	%		16.7	%
Dividend yield	-		1.5	%		1.7	%		1.4	%