Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Compensation, Restricted Stock Units Award Activity

The following table summarizes the activity and related information for RSUs for the periods presented below (in millions, except per share amounts):

	Restricted Stock Units Outstanding
	Number of Shares		Weighted-Average Grant Date Fair Value per Share
Balance—December 31, 2019	6.1		$	64.56
Granted	1.3		114.33
Forfeited	(0.1	)	68.19
Vested	(1.0	)	58.17
Balance—March 31, 2020	6.3		$	75.96

Schedule of Share-based Compensation, Shares Withheld for Taxes

The following summarizes the number and value of the shares withheld for employee taxes (in millions):

	Three Months Ended
	March 31, 2020		March 31, 2019
Shares withheld for taxes	0.3		0.4
Amount withheld for taxes	$	37.8	$	32.0

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following table summarizes the weighted-average assumptions relating to our employee stock options:

	Three Months Ended
	March 31, 2020		March 31, 2019
Expected term in years	4.4		4.4
Volatility	33.5	%	34.2	%
Risk-free interest rate	1.3	%	2.5	%
Dividend rate	—	%	—	%

Schedule of Share-based Compensation, Stock Options, Activity

The following table summarizes the stock option activity and related information for the periods presented below (in millions, except exercise prices and contractual life):

	Options Outstanding
	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Balance—December 31, 2019	2.7		$	50.37
Granted	0.5		114.48
Forfeited	—		59.28
Exercised	(0.2	)	40.02
Balance—March 31, 2020	3.0		$	62.41
Options vested and expected to vest—March 31, 2020	3.0		$	62.41	4.8	$	123.8
Options exercisable—March 31, 2020	1.5		$	39.50	3.5	$	90.3

Schedule of Share-based Compensation, Stock Options, Activity, Additional Information

Additional information related to our stock options is summarized below (in millions, except per share amounts):

	Three Months Ended
	March 31, 2020		March 31, 2019
Weighted-average fair value per share granted	$	33.82	$	27.12
Intrinsic value of options exercised	$	13.1	$	27.2
Fair value of options vested	$	6.0	$	4.2

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

Stock-based compensation expense, including stock-based compensation expense related to awards classified as liabilities, is included in costs and expenses as follows (in millions):

	Three Months Ended
	March 31, 2020		March 31, 2019
Cost of product revenue	$	0.4	$	0.4
Cost of service revenue	3.0		2.8
Research and development	10.9		9.4
Sales and marketing	25.7		25.4
General and administrative	5.3		5.0
Total stock-based compensation expense	$	45.3	$	43.0

Schedule of Employee Service Share based Compensation Allocation of Recognized Period Costs by Award Type

The following table summarizes stock-based compensation expense, including stock-based compensation expense related to awards classified as liabilities, by award type (in millions):

	Three Months Ended
	March 31, 2020		March 31, 2019
RSUs	$	42.2	$	39.2
Stock options	3.1		2.5
ESPP	—		1.3
Total stock-based compensation expense	$	45.3	$	43.0

Income Tax Benefit from Stock Option Plans

Total income tax benefit associated with stock-based compensation that is recognized in the condensed consolidated statements of income is as follows (in millions):

	Three Months Ended
	March 31, 2020		March 31, 2019
Income tax benefit associated with stock-based compensation	$	10.0	$	10.0