Stock Options, Restricted Stock Units and Employee Stock Purchase Plan (Tables)

3 Months Ended

Mar. 31, 2019

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

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table sets forth the components of the Company’s share-based compensation expense for the three month period ended March 31, 2019 and 2018 (in thousands):

	Three Months Ended March 31,
	2019		2018
Stock options	$	1,381	$	3,159
Employee stock purchase plan	229		—
Restricted stock units and Performance share units	3,110		2,349
Total stock-based compensation expense	$	4,720	$	5,508

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

Set forth in the following table are the weighted-average assumptions used in estimating the grant date fair value of the stock options granted under the Company's equity compensation plans during the three month period ended March 31, 2019, along with the weighted-average grant date fair values:

	Three Months Ended March 31,
	2019			2018
Expected volatility	67		%	—		%
Expected life (in years)	6.2			—
Risk-free interest rate	2.52		%	—		%
Dividend yield	—			—
Fair value per stock option	$	2.44		$	—
Forfeiture rate	8		%	—		%

Schedule of Share-based Compensation, Activity

The table below sets forth a summary of stock option activity within the Company’s stock-based compensation plans for the three month period ended March 31, 2019: 

	Number of Options (in thousands)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands) (1)
Outstanding at December 31, 2018	3,418		$	28.55	3.69	$	—
Granted	860		3.90
Exercised	—		—
Forfeited	(196	)	27.61
Outstanding at March 31, 2019	4,082		$	23.40	4.38	$	—
Exercisable at March 31, 2019	2,599		$	28.64	2.61	$	—

(1) The Aggregate Intrinsic Value of stock options outstanding and exercisable is defined as the difference between the market value of the Company’s common stock as of the date indicated and the exercise price of the stock options. Stock options for which the exercise price exceeded the market price have been omitted. Fluctuations in the intrinsic value of both outstanding and exercisable options may result from changes in underlying stock price and the timing and volume of option grants, exercises and forfeitures.

Schedule of Nonvested Restricted Stock Units Activity

Set forth below is a summary of unvested RSU activity during the three month period ended March 31, 2019:

	Number of Units (in thousands)	Weighted Average Per Share Grant Date Fair Value
Unvested at December 31, 2018	1,643	$	19.85
Granted	3,197	$	4.02
Vested	(273)	$	23.75
Forfeited	(153)	$	16.44
Unvested at March 31, 2019	4,414	$	9.52

Schedule of Nonvested Performance-based Units Activity

Set forth below is a summary of unvested PSU activity during the three month period ended March 31, 2019:

	Total Number of Units (in thousands)	Weighted Average Grant Date Fair Value per Unit		Vesting Based on Performance Conditions	Weighted Average Grant Date Fair Value per Unit		Vesting Based on Market Conditions	Weighted Average Grant Date Fair Value per Unit
Unvested at December 31, 2018	—	$	—	—	$	—	—	$	—
Granted	1,239	3.99		985	4.06		254	3.73
Vested	—	—		—	—		—	—
Forfeited	—	—		—	—		—	—
Unvested at March 31, 2019	1,239	$	3.99	985	$	4.06	254	$	3.73

Schedule of Share-based Payment Award, Performance Stock Units, Valuation Assumptions

Set forth below is a summary of the valuation inputs for PSUs granted with vesting subject to market conditions during the three month period ended March 31, 2019:

Valuation Inputs for PSUs with Vesting Subject to Market Conditions:
PSUs Issued (units in thousands)	254
Risk Free Rate	2.58		%
Volatility	55.10		%
Dividend	—		%
Valuation Per Share	$	3.73
Total Fair Value (in thousands)	$	947
Expected Term (years)	4
Forfeiture Rate Assumed	8.00		%