We are authorized by our Certificate of Incorporation to issue 60,000,000 shares of common stock, $0.001 par value and 5,000,000 shares of preferred stock, $0.001 par value. As of December 31, 2016, there were 35,253,577 and 33,597,215 shares of common stock issued and outstanding, respectively, and no shares of preferred stock issued or outstanding. Our Board of Directors is authorized to fix the dividend rights and terms, conversion and voting rights, redemption rights and other privileges and restrictions applicable to our preferred stock.

Our 2008 Omnibus Incentive Compensation Plan (the “Plan”) authorizes the grant of various types of equity-based awards, such as stock awards, restricted stock units, stock appreciation rights and stock options to eligible participants, which include all of our employees and all employees of our 50% or more owned subsidiaries, our non-employee directors and certain consultants. The vesting terms of the awards may be tied to continued employment (or, for our non-employee directors, continued service on the Board of Directors) and/or achievement of certain pre-determined performance goals. We refer to stock awards subject to service-based vesting conditions as “non-vested stock” and restricted stock units subject to service-based and performance-based or market-based vesting conditions as “non-vested stock units.” The Plan is administered by the Compensation Committee of our Board of Directors, which determines, within the provisions of the Plan, those eligible employees to whom, and the times at which, awards shall be granted. The Compensation Committee, in its discretion, may delegate its authority and duties under the Plan to specified officers; however, only the Compensation Committee may approve the terms of awards to our executive officers.

Equity-based awards may be granted for a number of shares not to exceed, in the aggregate, approximately 5.5 million shares of common stock, and we had approximately 1.2 million shares available at December 31, 2016. The price per share for stock options shall be of no less than the greater of (a) 100% of the fair value of a share of common stock on the date the option is granted or (b) the aggregate par value of the shares of our common stock on the date the option is granted. If a stock option is granted to any owner of 10% or more of our total combined voting power of us and our subsidiaries, the price is to be at least 110% of the fair value of a share of our common stock on the date the award is granted. Each equity-based award vests ratably over a 12 month to six year period, with the exception of those issued under contractual arrangements that specify otherwise, that may be exercised during a period as determined by our Compensation Committee or as otherwise approved by our Compensation Committee. The contractual terms of stock options exercised shall not exceed ten years from the date such option is granted.

We have a plan whereby our eligible employees may purchase our common stock at 85% of the market price at the time of purchase. On June 7, 2012, our stockholders ratified an amendment adopted by our Board of Directors to increase the total number of shares of our common stock authorized for the issuance under our ESPP from 2,500,000 shares to 4,500,000 shares, and as of December 31, 2016, there were 1,460,800 shares available for future issuance. The following is a detail of the purchases that were made or pending Board of Director approval under the plan:

Employee Stock Purchase Plan Period	Shares Issued	Price
2014 and Prior	2,899,528	$	13.78
January 1, 2015 to March 31, 2015	24,368		22.76
April 1, 2015 to June 30, 2015	15,750		33.77
July 1, 2015 to September 30, 2015	18,984		32.27
October 1, 2015 to December 31, 2015	19,082		33.42
January 1, 2016 to March 31, 2016	13,850		41.09
April 1, 2016 to June 30, 2016	14,236		42.91
July 1, 2016 to September 30, 2016	16,520		40.32
October 1, 2016 to December 31, 2016	16,882		36.24
	3,039,200

ESPP expense included in general and administrative expense in our accompanying consolidated statements of operations was $0.4 million for each of 2016, 2015 and 2014, respectively.

Stock Options

We use the Black-Scholes option pricing model to estimate the fair value of our stock options. There were 268,538, 590,647 and 250,000 options granted during 2016, 2015 and 2014, respectively. Stock option compensation expense included in general and administrative expense in our accompanying consolidated statements of operations was $6.3 million, $3.8 million and $0.1 million for 2016, 2015 and 2014, respectively.

The fair value of the 2016 awards were estimated using the following assumptions:

	Risk Free Rate	1.19% - 1.58%
	Expected Volatility	53.44 % - 54.89%
	Expected Term	5.86 - 6.25 years
	Weighted Average Fair Value	$25.99

We used the simplified method to estimate the expected term for the stock options granted during 2016.

The following table presents our stock option activity for 2016:
		Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Life (Years)
Outstanding options at January 1, 2016		838,494	$	30.18	9.31
	Granted	268,538		37.21
	Exercised	0		0
	Canceled, forfeited or expired	(98,875)		35.45
Outstanding options at December 31, 2016		1,008,157	$	31.54	8.42
Exercisable options at December 31, 2016		281,458	$	28.86	8.21

The aggregate intrinsic value of our outstanding options and exercisable options at December 31, 2016 was $11.9 million and $3.9 million, respectively. There were no options exercised during 2016. Total intrinsic value of options exercised was $0.2 million and $0.1 million for 2015 and 2014, respectively.

The following table presents our non-vested stock option award activity for 2016:
		Number of Shares	Weighted Average Grant Date Fair Value
		Number of Shares	Weighted Average Grant Date Fair Value
Non-vested stock options at January 1, 2016		775,994	$	30.47
	Granted	268,538		37.21
	Vested	(219,872)		29.55
	Forfeited	(97,961)		35.38
Non-vested stock options at December 31, 2016		726,699	$	32.58

At December 31, 2016, there was $7.2 million of unrecognized compensation cost related to stock options that we expect to be recognized over a weighted-average period of 2.1 years.


Non-Vested Stock

We issue shares of non-vested stock with vesting terms ranging from one to six years. The compensation expense is determined based on the market price of our common stock at the date of grant applied to the total number of shares that are anticipated to fully vest. Non-vested stock compensation expense included in general and administrative expenses in our accompanying consolidated statements of operations was $2.3 million, $5.0 million and $4.6 million for 2016, 2015 and 2014, respectively.

The following table presents our non-vested stock award activity for 2016:
		Number of Shares	Weighted Average Grant Date Fair Value
Non-vested stock at January 1, 2016		500,888	$	18.24
	Granted	21,202		50.55
	Vested	(222,783)		18.00
	Canceled, forfeited or expired	(89,929)		17.26
Non-vested stock at December 31, 2016		209,378	$	22.20

The weighted average grant date fair value of non-vested stock granted was $50.55, $28.48 and $16.38 in 2016, 2015, and 2014, respectively.

At December 31, 2016, there was $1.4 million of unrecognized compensation cost related to non-vested stock award payments that we expect to be recognized over a weighted average period of 0.9 years.

We issue non-vested stock unit awards that are service-based, performance-based or a combination of both with vesting terms ranging from one to six years. Based on the terms and conditions of these awards, we determine if the awards should be recorded as either equity or liability instruments. The compensation expense is determined based on the market price of our common stock at the date of grant, applied to the total number of units that are anticipated to vest, unless the award specifies differently. We account for such awards similar to our non-vested stock awards; however, no shares of stock are issued to the recipient until the stock unit awards have vested and after the pre-determined delivery date has occurred.


Non-Vested Stock Units - Service-Based

Service-based non-vested stock unit compensation expense included in general and administrative expenses in our accompanying consolidated statements of operations was $3.6 million and $1.0 million for 2016 and 2015, respectively.



The following table presents our service-based non-vested stock units activity for 2016:
		Number of Shares	Weighted Average Grant Date Fair Value
Non-vested stock units at January 1, 2016		183,332	$	37.89
	Granted	147,896		45.60
	Vested	(32,607)		38.81
	Canceled, forfeited or expired	(49,192)		39.38
Non-vested stock units at December 31, 2016		249,429	$	42.05

The weighted average grant date fair value of service-based non-vested stock units granted was $45.60 and $37.98 in 2016 and 2015, respectively.

At December 31, 2016, there was $6.7 million of unrecognized compensation cost related to our service-based non-vested stock units that we expect to be recognized over a weighted average period of 2.2 years.

During 2016, we awarded performance-based awards to certain employees. The target level established by the award, which is based on the Company's 2016 adjusted earnings before interest, taxes and depreciation (“EBITDA”), provided for the recipients to receive 182,796 non-vested stock units if the target was achieved. The target number of shares to be potentially awarded has been reduced by forfeitures as indicated in the table below. Performance-based non-vested stock units compensation expense included in general and administrative expenses in our consolidated statements of operations was $3.7 million and $1.3 million for 2016 and 2015, respectively.


The following table presents our performance-based non-vested stock units activity for 2016:
		Number of Shares	Weighted Average Grant Date Fair Value
Non-vested stock units at January 1, 2016		151,063	$	39.44
	Granted	182,796		46.29
	Vested	(44,729)		34.83
	Canceled, forfeited or expired	(64,273)		42.41
Non-vested stock units at December 31, 2016		224,857	$	45.08

The weighted average grant date fair value of performance-based non-vested stock units granted was $46.29 and $39.54 in 2016 and 2015, respectively.

At December 31, 2016, there were $6.4 million in unrecognized compensation costs related to our performance-based non-vested stock units that we expect to be recognized over a weighted average period of 2.0 years.

During 2013, we awarded market-based awards to certain employees. The target level established by the award, which was based on our average December 2015 stock price, provided for the recipients to receive 417,330 non-vested stock units if the target is achieved. If the target objective was surpassed to the point of achieving the projected maximum payout, the recipients would receive 667,728 non-vested stock units. The target number of shares to be potentially awarded was reduced by forfeitures as indicated in the table below. As of March 3, 2016, it was determined that the market-based objective established by the award was satisfied at maximum payout and as a result, 248,654 stock units were awarded to the recipients on April 1, 2016.

For market-based awards, the effect of the market condition is reflected in the fair value of the awards at the date of grant using a Monte-Carlo simulation model. A Monte-Carlo simulation model estimates the fair value of the market-based award based upon the expected term, risk-free interest rate and expected volatility. Compensation expense for market-based awards is recognized over the vesting period regardless of whether the market conditions are expected to be achieved. Market-based non-vested stock units compensation expense included in general and administrative expenses in our accompanying consolidated statements of operations was $0.1 million, $0.3 million and $0.5 million for 2016, 2015 and 2014, respectively. The fair value of the 2013 award was estimated using the following assumptions:


The following table presents our market-based non-vested stock units activity for 2016:
		Number of Shares	Weighted Average Grant Date Fair Value
Non-vested stock units at January 1, 2016		164,534	$	10.51
	Granted (1)	93,257		10.51
	Vested	(248,654)		10.51
	Canceled, forfeited or expired	(9,137)		10.51
Non-vested stock units at December 31, 2016		-	$	0


(1)	Represents shares awarded upon achievement of maximum payout.

The weighted average grant date fair value of market-based non-vested stock units granted was $10.51 in 2013. All of our outstanding market-based non-vested stock units were fully vested as of April 1, 2016.