Common Stock and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Class of Treasury Stock

We repurchased the following shares of common stock with cash resources:

	Year Ended December 31,
	2020		2019		2018
Shares of common stock repurchased	774,489		317,429		1,348,563
Cash paid for repurchases of common stock	$	34,999	$	17,961	$	73,105

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

The fair value of stock options granted to employees, directors, and consultants is estimated using the following assumptions:

	Year Ended December 31,
	2020	2019	2018
Risk-free interest rate	0.37% - 1.65%	1.42% - 2.61%	2.30% - 3.07%
Volatility	54.89% - 55.51%	40.83% - 50.73%	43.76%
Expected term (in years)	5.50 - 6.08 years	1.51 - 9.41 years	5.50 - 6.08 years
Expected dividend yield	0.0%	0.0%	0.0%

Share-based Compensation Arrangement by Share-based Payment Award

The following table summarizes information about stock option activity related to the 2014 Plan:

	Number of Stock Option Shares	Weighted Average Exercise Price (Per Share)		Non- Exercisable	Exercisable
Outstanding at December 31, 2018	2,556,365	$	62.78	1,074,456	1,481,909
Granted	628,133	$	44.28
Exercised	(23,032)	$	10.33
Forfeited or expired	(65,305)
Outstanding at December 31, 2019	3,096,161	$	59.29	1,070,054	2,026,107
Granted	762,200	$	55.76
Exercised	(149,473)	$	24.43
Forfeited or expired	(376,998)	$	66.71
Outstanding at December 31, 2020	3,331,890	$	59.20	1,028,142	2,303,748

Schedule of Restricted Stock Unit Activity

The following table summarizes information about RSU activity related to the 2014 Plan:

	Number of Restricted Stock Units	Weighted Average Grant Date Fair Value (Per Share)
Non-vested at December 31, 2018	54,219	$	59.02
Granted	211,829	$	42.17
Vested	(13,555)	$	59.02
Forfeited	(1,278)	$	52.19
Non-vested at December 31, 2019	251,215	$	44.84
Granted	236,450	$	59.48
Vested	(79,420)	$	46.78
Forfeited	(79,849)	$	52.76
Non-vested at December 31, 2020	328,396	$	53.09

Schedule of Phantom Share Unit Activity

The following table summarizes information about PSU activity related to the 2014 Plan:

	Number of Performance Stock Units	Weighted Average Grant Date Fair Value (Per Share)
Non-vested at December 31, 2018	117,219	$	90.19
Granted	—	$	—
Vested	—	$	—
Forfeited	(1,038)	$	90.19
Non-vested at December 31, 2019	116,181	$	90.19
Granted	—	$	—
Vested	—	$	—
Forfeited	(18,431)	$	90.19
Non-vested at December 31, 2020	97,750	$	90.19

Schedule of Share-based Compensation Cost

The Company recognized stock-based compensation in its consolidated statements of income for the year ended December 31, 2020, 2019, and 2018 as follows:

	Year Ended December 31,
	2020		2019		2018
Stock options	$	17,694	$	16,394	$	15,333
PSUs	1,635		3,062		3,059
RSUs	5,427		2,542		690
Stock-based compensation expense	$	24,756	$	21,998	$	19,082
Selling, general and administrative	$	22,074	$	17,556	$	15,068
Research and development	2,682		4,442		4,014
Stock-based compensation expense	$	24,756	$	21,998	$	19,082