Document and Entity Information - shares
3 Months Ended
Dec. 31, 2016
Feb. 01, 2017
Document And Entity Information [Abstract]    
Entity Registrant Name EMCORE CORPORATION  
Entity Central Index Key 0000808326  
Document Type 10-Q  
Document Period End Date Dec. 31, 2016  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2016  
Current Fiscal Year End Date --09-30  
Entity Filer Category Accelerated Filer  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   26,584,521