Stock-Based Compensation (Summary of Option Activity) (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
2005 Plan [Member]
Stock Options
Outstanding at January 1, 2016	15,450,542
Granted	0
Exercised	(511,650)
Canceled	(136,875)
Outstanding at March 31, 2016	14,802,017
Shares exercisable at March 31, 2016	10,041,892
Weighted-Average Exercise Price
Outstanding at January 1, 2016 | $ / shares	$ 3.31
Granted | $ / shares	0
Exercised | $ / shares	1.72
Canceled | $ / shares	4.48
Outstanding at March 31, 2016 | $ / shares	3.35
Shares available for grant at March 31, 2016 | $ / shares	$ 2.79
2015 Plan [Member]
Stock Options
Outstanding at January 1, 2016	8,357,003
Granted	9,723,437
Exercised	0
Canceled	(123,526)
Outstanding at March 31, 2016	17,956,914
Shares exercisable at March 31, 2016	1,916,292
Shares available for grant at March 31, 2016	6,998,086
Weighted-Average Exercise Price
Outstanding at January 1, 2016 | $ / shares	$ 8.97
Granted | $ / shares	4.99
Exercised | $ / shares	0
Canceled | $ / shares	8.37
Outstanding at March 31, 2016 | $ / shares	6.82
Shares available for grant at March 31, 2016 | $ / shares	$ 8.94