Net Income (Loss) Per Share Net Income (Loss) Per Share - Anti Diluted Shares Excluded (Details) - shares shares in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	[1]	8,201	8,931	8,696
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		3,327	4,470	5,295
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		2,997	3,059	2,536
Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		609	620	659
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	[2]	1,268	782	206

[1] Excluded from the table above are the Notes, which are convertible under certain conditions into an aggregate of 22,304,348 shares of common stock. See Note 11, “Convertible Notes, Other Debts and Capital Leases,” for additional information on the Notes. Since the Company’s intent is to settle the principal amount of the Notes in cash, the treasury stock method is being used to calculate any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. The conversion spread will have a dilutive impact on diluted net income per share when the Company’s average market price of its common stock for a given period exceeds the conversion price of $5.75 per share.

[2] In 2016, in connection with the execution of a product supply agreement the Company granted Comcast a warrant to purchase shares of its common stock. See Note 16, “Warrants,” for additional information. The warrants will have a dilutive impact on diluted net income per share when the Company’s average market price of its common stock for a given period exceeds the warrant exercise price of $4.76 per share.