Stock-Based Compensation

We maintain stock incentive plans for the benefit of certain officers, directors, and employees, including the 2013 Omnibus Incentive Plan (the "2013 Plan"). Compensation expense for stock-based awards is based on the fair values of the awards on the date of grant and is recognized on a straight-line basis over the vesting period of the entire award in the “Labor” line of the Consolidated Statements of Comprehensive Loss. We recognized $1.8 million and $2.4 million of stock-based compensation expense during the nine months ended September 30, 2017 and 2016, respectively.

All stock-based awards granted during the nine months ended September 30, 2017 were granted under the 2013 Plan.

Stock Options

Stock options become exercisable in 25% increments on the first four anniversaries of the grant date, and expire on the tenth anniversary of their grant date. Options are granted at an exercise price equal to the market value of the common stock at the market close on the day prior to the grant. Options granted prior to the 2013 Plan will remain outstanding in accordance with their respective terms.

The following table summarizes all stock option activity for the nine months ended September 30, 2017:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)
Balance as of December 31, 2016	3,705,893		$	7.72	4.74
Granted	—		—
Exercised	—		—
Forfeited	(89,630	)	7.13
Vested options expired	(847,898	)	11.07
Balance as of September 30, 2017	2,768,365		6.72		5.10

Vested and expected to vest as of September 30, 2017	2,768,365		$	6.72	5.10

Exercisable as of September 30, 2017	2,003,764		$	7.59	3.73

As of September 30, 2017, there was $0.7 million of total unrecognized compensation cost related to unvested stock options. This cost is expected to be recognized over a weighted average period of approximately 1.82 years.

Cash Stock Appreciation Rights

During the nine months ended September 30, 2017, the Board approved cash settling stock appreciation rights under the 2013 Plan.

Cash stock appreciation rights vest in 25% increments on the first four anniversaries of the grant date. Cash stock appreciation rights settle solely in cash and are treated as a liability.

The following table summarizes all stock appreciation rights activity for the nine months ended September 30, 2017:



	Number of Shares	Weighted Average Grant-Date Fair Value
Balance as of December 31, 2016	—	$	—
Granted	866,196	0.97
Vested	—	—
Forfeited	—	—
Cash stock appreciation rights outstanding at September 30, 2017	866,196	$	0.97

As of September 30, 2017, there was $0.5 million of total unrecognized compensation cost related to cash stock appreciation rights. The cost is expected to be recognized over a weighted average period of approximately 3.73 years. Changes in our stock price, the volatility of our stock price, and the risk-free rate of interest will result in adjustments to compensation expense and the corresponding liability over the applicable service period.

Unvested Shares

Unvested shares vest in three equal increments on the first three anniversaries of their grant date. Unvested shares settle solely in common stock and are treated as equity.

The following table summarizes all unvested share activity for the nine months ended September 30, 2017:



	Number of Shares		Weighted Average Grant- Date Fair Value
Balance as of December 31, 2016	945,252		$	3.76
Granted	1,336,060		0.98
Vested	(405,241	)	4.13
Forfeited	(132,468	)	2.76
Unvested shares outstanding at September 30, 2017	1,743,603		$	1.61

As of September 30, 2017, there was $2.3 million of total unrecognized compensation cost related to unvested shares. This cost is expected to be recognized over a weighted average period of approximately 1.96 years.

Phantom Stock Units

Phantom stock units vest in 25% increments on the first four anniversaries of the grant date. Phantom stock units settle solely in cash and are treated as a liability.

The following table summarizes all phantom stock activity for the nine months ended September 30, 2017:



	Number of Shares		Weighted Average Grant- Date Fair Value
Balance as of December 31, 2016	531,820		$	2.69
Granted	560,000		0.97
Settled	(125,046	)	2.69
Forfeited	(112,360	)	2.51
Phantom stock units outstanding at September 30, 2017	854,414		$	1.59

As of September 30, 2017, there was $0.8 million of total unrecognized compensation cost related to phantom stock. This cost is expected to be recognized over a weighted average period of approximately 3.32 years. Changes in our stock price will result in adjustments to compensation expense and the corresponding liability over the applicable service period.

Performance Stock Units

Performance stock units vest in a range between 0% to 100% based upon certain performance criteria in a three-year period. At the end of the performance period, the number of shares paid will be based on our performance versus the target. Performance stock units settle solely in common stock and are treated as equity.

The following table summarizes all performance stock unit activity for the nine months ended September 30, 2017:



	Number of Shares		Weighted Average Grant- Date Fair Value
Balance as of December 31, 2016	844,315		$	2.56
Granted	711,268		0.99
Settled	—		—
Forfeited	(104,946	)	4.79
Performance stock units outstanding at September 30, 2017	1,450,637		$	1.63

As of September 30, 2017, there was $1.3 million of total unrecognized compensation cost related to performance stock units. This cost is expected to be recognized over a weighted average period of approximately 1.90 years.

Cash Performance Stock Units

Cash performance stock units vest in a range between 0% to 100% based upon certain performance criteria measured over a three-year period. At the end of the performance period, the number of shares settled in cash will be based on our performance versus the target. Cash performance stock units settle solely in cash and are treated as a liability.

The following table summarizes all cash performance stock unit activity for the nine months ended September 30, 2017:



	Number of Shares		Weighted Average Grant- Date Fair Value
Balance as of December 31, 2016	444,005		$	2.69
Granted	1,098,871		1.01
Settled	—		—
Forfeited	(37,784	)	2.69
Cash performance stock units outstanding at September 30, 2017	1,505,092		$	1.46

As of September 30, 2017, there was $1.1 million of total unrecognized compensation cost related to performance stock units. This cost is expected to be recognized over a weighted average period of approximately 2.38 years. Changes in our stock price will result in adjustments to compensation expense and the corresponding liability over the applicable service period. Expense is also adjusted up or down based on the current estimate of future performance against the established performance goals.