Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Stock option activity for the year ended December 31, 2019 was as follows:


				Weighted
				Average
	Shares	Weighted		Remaining	Aggregate
	Subject to	Average		Contractual	Intrinsic Value
	Options	Option Price		Term (Yrs)	(in millions) (b)
Outstanding at December 31, 2018	2,593,310	$	21.41
Granted	112,232		44.17
Exercised	(626,796)		19.22
Forfeited/Expired	(90,050)		22.50
Outstanding at December 31, 2019	1,988,696	$	23.43	4.9	$	54.8
Exercisable at December 31, 2019	1,537,624	$	20.97	4.7	$	46.1
Exercisable and expected to vest at December 31, 2019 (a)	1,951,167	$	23.27	4.9	$	54.1

(a)	In addition to the options that are vested at December 31, 2019, the Company expects a portion of the unvested options to vest in the future. Options expected to vest in the future are determined by applying an estimated forfeiture rate to the options that are unvested as of December 31, 2019.

(b)	The aggregate intrinsic value is based on the positive difference between the fair value of the Company’s common stock price of $50.97 on December 31, 2019, or the date of exercises, as appropriate, and the exercise price of the underlying stock options.

The following table summarizes information about restricted stock award activity during the year ended December 31, 2019:

The following table summarizes information about restricted stock unit activity for year ended December 31, 2019: