Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

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

Key Assumptions Utilized in Determining Fair Value of Awards Granted

The key assumptions utilized in determining the fair value of the stock options granted during the years ended December 31, 2015, 2014 and 2013 are as follows for the various tranches:

	Time-Based Options
	Year Ended December 31,
	2015	2014	2013
Assumptions:
Expected term (years)	2.07 - 7.50	2.07 - 7.50	2.81 - 7.50
Expected volatility	45.00% - 77.00%	47.00% - 77.00%	64.00% - 84.00%
Risk-free interest rate	0.46% - 2.31%	0.46% - 2.31%	0.34% - 1.35%
Expected dividend yield	—%	—%	—%

	Performance-Based Options
	Year Ended December 31,
	2015	2014	2013
Assumptions:
Expected term (years)	2.07 - 4.30	2.07 - 4.30	2.80 - 3.80
Expected volatility	44.00% - 74.00%	44.00% - 74.00%	64.00% - 83.00%
Risk-free interest rate	0.29% - 3.09%	0.29% - 3.09%	0.34% - 2.50%
Expected dividend yield	—%	—%	—%

Outstanding and Exercisable Stock Options, By Exercise Price

	Outstanding				Exercisable
Exercise Price	Options	Weighted- Average Remaining Contractual Term (In years)	Weighted- Average Exercise Price		Options	Weighted- Average Exercise Price
$6.64	5,044,408	7.2	$	6.64	4,648,885	$	6.64
$20.00	1,252,381	9.5	20.00		—	—
Total	6,296,789	7.7	$	9.30	4,648,885	$	6.64

Stock Option Activity

	Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In millions)
Outstanding at December 31, 2014	5,262,914		$	6.64
Granted	1,297,772		19.62
Exercised	(47,835	)	6.64
Expired	(157,402	)	6.64
Forfeited	(58,660	)	8.50
Outstanding at December 31, 2015	6,296,789		$	9.30	7.7	$	29.6
Exercisable at December 31, 2015	4,648,885		$	6.64	7.3	$	27.3
Options expected to vest	6,034,302		$	8.86	7.6	$	29.5