Stock Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Options, Valuation Assumptions

Key assumptions used in the valuation models were as follows for the years ended December 31:

	2019	2018	2017
Expected volatility	37.90% - 40.02%	34.81% - 39.68%	37.36% - 42.83%
Expected dividend yield rate	0.00%	0.00%	0.00%
Weighted average term (in years)	5.50 - 6.50	5.50 - 6.50	5.50 - 6.50
Weighted average grant date fair value	$8.32	$12.98	$11.51
Risk free rate	1.79% - 2.50%	2.04% - 2.96%	1.83% - 2.19%

Stock Option Activity Rollforward

The following table represents stock option activity:

	Shares	Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value (millions)		Weighted Average Remaining Contract Term in Years
Outstanding as of January 1, 2017	5,156,976	$	20.40
Issued upon conversion of class B-1 Common Stock	2,494,553	11.13
Granted	505,122	27.78
Exercised	(2,781,055)	11.67
Forfeited	(448,928)	15.01
Balance as of December 31, 2017	4,926,668	$	14.56
Granted	838,912	32.16
Exercised	(1,548,484)	13.79
Forfeited	(884,391)	18.8
Balance as of December 31, 2018	3,332,705	$	18.22
Granted	443,170	20.94
Exercised	(641,706)	10.56
Forfeited	(301,370)	26.07
Balance as of December 31, 2019	2,832,799	$	19.55	$	17.0	5.9
Exercisable as of December 31, 2019	1,755,821	$	16.47	$	14.6	4.6

RSU and PSU Activity Rollforward

The following table represents RSU activity:

	Shares	Weighted Average Grant-Date Fair Value Per Share
Outstanding as of January 1, 2017	385,220	$	22.00
Granted	365,972	28.89
Vested	(175,110)	18.40
Forfeited	(13,714)	26.02
Balance as of December 31, 2017	562,368	$	27.51
Granted	766,927	29.14
Vested	(124,560)	25.21
Forfeited	(530,867)	29.69
Balance as of December 31, 2018	673,868	$	28.07
Granted	952,801	20.07
Vested	(232,666)	30.08
Forfeited	(154,498)	23.38
Balance as of December 31, 2019	1,239,505	$	22.13

The following table represents PSU activity for the awarded shares at target performance measures:

	Shares	Weighted Average Grant-Date Fair Value Per Share
Outstanding as of January 1, 2018	—	$	—
Granted	193,763	31.60
Forfeited	(19,093)	33.31
Balance as of December 31, 2018	174,670	$	31.41
Granted	401,935	22.21
Forfeited	(65,832)	25.24
Balance as of December 31, 2019	510,773	$	24.97