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Stockholders' Equity (Narrative) (Details)
 1 Months Ended 12 Months Ended
Jan. 31, 2017
shares
Dec. 31, 2016
USD ($)
item
$ / shares
shares
Dec. 31, 2015
USD ($)
$ / shares
shares
Dec. 31, 2014
USD ($)
$ / shares
shares
Feb. 02, 2017
USD ($)
May 18, 2016
USD ($)
Feb. 03, 2016
USD ($)
Feb. 03, 2015
USD ($)
Nov. 08, 2013
USD ($)
Feb. 28, 2013
$ / shares
shares
Oct. 05, 2012
USD ($)
Oct. 31, 2010
$ / shares
shares
Stockholders' Equity [Line Items]                        
Common Stock, shares authorized | shares   1,000,000,000 1,000,000,000                 1,000,000,000
Common Stock, par value | $ / shares   $ 0.001 $ 0.001                 $ 0.001
Preferred Stock, shares authorized | shares   50,000,000 50,000,000                 50,000,000
Preferred Stock, par value | $ / shares   $ 0.001 $ 0.001                 $ 0.001
Preferred Stock, shares issued | shares   0 0                  
Preferred Stock, shares outstanding | shares   0 0                  
Common stock, dividends declared | $ / shares   $ 0                    
Voting right of common stock share holders   one                    
Voting right of common stock share holdes, number of votes | item   1                    
Proceeds from issuance of common stock   $ 7,729,000 $ 7,363,000 $ 3,968,000                
Number of warrants net exercised | shares   5,500,000                    
Number of shares of common stock called by issuance of warrants | shares   4,200,000               5,500,000    
Aggregate exercise price of common stock called by issuance of warrants | $ / shares                   $ 2.63    
Number of shares of common stock called by issuance of warrants, outstanding | shares   0                    
Number of equity compensation plans | item   3                    
Aggregate intrinsic value outstanding   $ 7,300,000                    
Aggregate intrinsic value exercisable options   $ 6,300,000                    
Stock price | $ / shares   $ 3.80                    
Weighted average remaining contractual life for exercisable   5 years 7 months 13 days                    
Vested and expected to vest, outstanding | shares   19,636,962                    
Vested and expected to vest, aggregate intrinsic value   $ 6,900,000                    
Vested and expected to vest, weighted average exercise price | $ / shares   $ 6.17                    
Vested and expected to vest, weighted average remaining contractual life   6 years 4 months 2 days                    
Total intrinsic value of options exercised   $ 4,700,000 3,500,000 2,000,000                
Fair value of options vested   20,700,000 7,300,000 6,000,000                
Stock-based compensation cost capitalized in inventory   389,000 315,000                  
Stock-based compensation   $ 19,562,000 $ 13,840,000 $ 9,943,000                
2010 Plan [Member]                        
Stockholders' Equity [Line Items]                        
Stock option grant, term   10 years                    
Stock option grant, vest   4 years                    
Stock option grant, vest rate upon first anniversary   25.00%                    
Stock option grant, vest rate per month thereafter   2.08%                    
2010 Director Plan [Member]                        
Stockholders' Equity [Line Items]                        
Stock option grant, term   10 years                    
Stock option grant, vest rate upon first anniversary   33.00%                    
Stock option grant, vest rate per month thereafter   2.78%                    
2010 Director Plan [Member] | Minimum [Member]                        
Stockholders' Equity [Line Items]                        
Stock option grant, vest   1 year                    
2010 Director Plan [Member] | Maximum [Member]                        
Stockholders' Equity [Line Items]                        
Stock option grant, vest   3 years                    
2010 Plan and 2010 Director Plan [Member]                        
Stockholders' Equity [Line Items]                        
Common stock reserved for issuance | shares   6,500,000                    
ESPP [Member]                        
Stockholders' Equity [Line Items]                        
Common stock reserved for issuance | shares   738,063                    
Percentage of outstanding common stock used to determine annual plan increase   2.00%                    
Number of purchase periods | item   4                    
Purchase period of ESPP   6 months                    
Percentage of fair market value at which stock can be purchased   85.00%                    
Weighted average fair value at grant date | $ / shares   $ 4.21 $ 2.20 $ 2.98                
Stock-based compensation   $ 3,700,000 $ 3,600,000 $ 2,100,000                
Common stock purchased under plan | shares   1,300,000 1,100,000 1,300,000                
Cash received from option exercises   $ 5,200,000 $ 4,400,000 $ 2,300,000                
At the Market Offering [Member]                        
Stockholders' Equity [Line Items]                        
Common stock offering price shares           $ 30,000,000 $ 30,000,000 $ 30,000,000 $ 30,000,000   $ 30,000,000  
Commissions   3.00%                    
Stock Options [Member]                        
Stockholders' Equity [Line Items]                        
Weighted average remaining contractual life   2 years 8 months 12 days                    
Weighted average fair value at grant date | $ / shares   $ 5.47 $ 4.75 $ 3.81                
Stock-based compensation   $ 15,700,000 $ 10,200,000 $ 7,800,000                
Unrecognized compensation costs   23,400,000                    
Cash received from option exercises   $ 2,500,000 $ 3,000,000 $ 1,600,000                
Subsequent Event [Member] | 2010 Plan [Member]                        
Stockholders' Equity [Line Items]                        
Additional common stock reserved for issuance | shares 4,600,000                      
Subsequent Event [Member] | ESPP [Member]                        
Stockholders' Equity [Line Items]                        
Additional common stock reserved for issuance | shares 1,900,000                      
Subsequent Event [Member] | At the Market Offering [Member]                        
Stockholders' Equity [Line Items]                        
Common stock offering price shares         $ 60,000,000              
Notes [Member]                        
Stockholders' Equity [Line Items]                        
Holders may elect to receive net proceeds from financing activities, percentage   25.00%