STOCK-BASED COMPENSATION

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-based compensation expense related to awards issued under the Company's incentive compensation plans for the three months ended March 31, 2020 and 2019 was as follows (in millions):



	Three Months Ended March 31,
	2020		2019
Cost of sales	$	4.6	$	4.0
Selling, general, and administrative expenses	14.4		12.7
Research and development expenses	4.9		4.1
Total stock-based compensation expense	$	23.9	$	20.8

At March 31, 2020, the total remaining compensation cost related to nonvested stock options, restricted stock units, market-based restricted stock units, performance-based restricted stock units, and employee stock purchase plan ("ESPP") subscription awards amounted to $119.1 million, which will be amortized on a straight-line basis over the weighted-average remaining requisite service period of 28 months.

Fair Value Disclosures

The following table includes the weighted-average grant-date fair values of stock options granted during the periods indicated and the related weighted-average assumptions used in the Black-Scholes option pricing model:



Option Awards	Three Months Ended March 31,
	2020			2019
Average risk-free interest rate	1.4		%	2.5		%
Expected dividend yield	None			None
Expected volatility	29.7		%	29.2		%
Expected term (years)	5.2			5.2
Fair value, per option	$	68.36		$	54.03

The following table includes the weighted-average grant-date fair values for ESPP subscriptions granted during the periods indicated and the related weighted-average assumptions used in the Black-Scholes option pricing model:



ESPP	Three Months Ended March 31,
	2020			2019
Average risk-free interest rate	1.6		%	2.4		%
Expected dividend yield	None			None
Expected volatility	31.9		%	25.3		%
Expected term (years)	0.6			0.6
Fair value, per share	$	47.14		$	48.83