Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2013

Stock-Based Compensation [Abstract]

Information about Stock Options

The following tables summarize information about stock-options and RSU's outstanding at December 31, 2013:

Options Outstanding									Options Vested and Exercisable
Date of Option Issue	Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price
2006	$	0.24		690,612		2.22	$	0.24		690,612		2.22	$	0.24
2007	$	4.20		1,277,574		3.56		4.20		1,277,574		3.56		4.20
2007	$	5.88-6.47		563,931		3.99		5.88		563,931		3.99		5.88
2008	$	1.74-6.20		169,500		4.37		5.13		169,500		4.37		5.13
2009	$	1.15- 1.58		933,211		5.26		1.16		933,211		5.26		1.16
2010	$	5.48-6.03		279,896		6.17		5.49		268,440		6.17		5.49
2011	$	19.85-23.62		425,000		7.37		23.62		290,416		7.37		23.62
2012	$	23.84 – 35.25		362,500		8.39		27.00		164,166		8.35		27.16
2013	$	23.72 – 35.05		274,625		9.37		25.37		52,561		9.36		25.70
				4,976,849		4.91	$	7.86		4,410,411		4.45	$	5.66

	RSU's Outstanding
Grant Date	Range of Grant Prices			Number Outstanding		Weighted Average Grant Price
2012		$	24.75 – 29.90		92,500		$	24.75
2013		$	23.72		156,415			23.72
					248,915		$	24.10

Stock Option Activity

The following tables summarize activity under the Plan for the indicated periods:

	Options
	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2010		4,830,391		$	3.14		—		—
Options granted		475,000			23.80		—		—
Options exercised		(398,393	)		2.68		—		—
Options cancelled		—			—		—		—
Outstanding at December 31, 2011		4,906,998			5.12		—		—
Options granted		367,500			26.97		—		—
Options exercised		(486,165	)		3.48		—		—
Options cancelled		(12,109	)		17.34		—		—
Outstanding at December 31, 2012		4,776,224			6.94		—		—
Options granted		274,625			25.37		—		—
Options exercised		(39,833	)		4.27		—		—
Options cancelled		(34,167	)		20.57		—		—
Outstanding at December 31, 2013		4,976,849		$	7.86		4.91	$	63,649

	RSU's
	Number of RSU's			Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
Outstanding at December 31, 2011		—			—		—
RSU's granted		151,665			25.60		—
Outstanding at December 31, 2012		151,665		$	25.60	$	—
RSU's granted		156,415			23.72		—
RSU's vested		(55,832	)		27.06		—
RSU's cancelled		(3,333	)		24.75		—
Outstanding at December 31, 2013		248,915		$	24.10	$	—

Share-Based Compensation by Type of Award

Stock-based compensation expense is included in general and administrative expense for each period as follows:

Stock-Based Compensation by Type of Award	Year Ended December 31, 2013		Year Ended December 31, 2012		Year Ended December 31, 2011
Employee stock options	$	6,488	$	5,171	$	4,367
RSU’s		1,075		991		—
Total stock-based compensation expense	$	7,563	$	6,162	$	4,367

Fair Value Assumptions

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted average assumptions:

	Year Ended December 31, 2013			Year Ended December 31, 2012			Year Ended December 31, 2011
Expected stock price volatility		93	%		111	%		123	%
Risk-free interest rate		2.04	%		1.90	%		3.05	%
Expected life term (in years)	6.10 years			6.8 years			6.6 years
Expected dividends		0	%		0	%		0	%