Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used to Determine Fair Value of Stock Options Granted

The assumptions used to determine the fair value of the stock options granted during the years ended December 31, 2014, 2013 and 2012 were as follows:

	2014			2013			2012
Weighted-average fair value options granted	$	13.87		$	3.97		$	1.46
Average risk-free interest rate		1.97	%		1.41	%		0.87	%
Expected stock price volatilities_(a)		50.3	%		50.7	%		54.8	%
Dividend yield	None			None			None
Expected stock option life (years)		6.26			5.20			6.11

There was no active external or internal market for the Company’s shares until April of 2014. Thus, it was not possible to estimate the expected volatility of the Company’s share price in estimating fair value of options granted. As a substitute for such volatility, the Company used the historical volatility of comparable companies.

Summary of Stock Option Activity

Stock option awards as of December 31, 2014 and 2013, and changes during the year ended December 31, 2014, were as follows:

	Options			Weighted-Average Exercise Price		Average Intrinsic Value (thousands)		Weighted-Average Exercise Term (years)
Outstanding at December 31, 2013		7,669,553		$	4.08	$	56,844		8.29
Granted		2,019,413			18.35
Forfeited		(953,472	)		6.68
Exercised_(a)		(2,554,699	)		3.73
Outstanding at December 31, 2014		6,180,795			8.49		172,661		7.87
Vested and expected to vest at December 31, 2014		4,738,666			7.56		138,012		7.73
Exercisable at December 31, 2014		2,506,615		$	4.02	$	80,962		7.22
·Included 138,048 shares of restricted common stock owned by officers of the Company that contained forfeiture provisions. ___________________________________________

Non-vested Restricted Stock Unit Awards

Non-vested restricted stock unit awards as of December 31, 2014 and 2013, and changes during the year ended December 31, 2014 were as follows:

	Shares		Weighted-Average Grant Date Fair Value
Outstanding at December 31, 2013		—	$	—
Granted		2,899		31.90
Forfeited		—		—
Vested		—		—
Outstanding at December 31, 2014		2,899	$	31.90