Accounts Receivable - Other Disclosures (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011
Disclosures:
Billed Contracts Receivable, Using Percentage of Completion Method	$ 1.4	$ 1.3
Unbilled Contracts Receivable, Using Percentage of Completion Method	4.7	2.0
Accounts Receivable, Gross, Using Percentage Of Completion Method	$ 6.1	$ 3.3

Gross amounts due for billed and unbilled services rendered or to be rendered or actions taken or to be taken in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party, being accounted for by the Company using the percentage of completion method.

No definition available.

Name:	emkr_AccountsReceivableGrossUsingPercentageOfCompletionMethod
Namespace Prefix:	emkr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant