Acquisitions Of Businesses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Business Acquisition [Line Items]
Non-cash income from contingent consideration arrangements	$ 0.2	$ 0

Non-cash income (expense) from acquisition related contingent consideration arrangements.

No definition available.

Name:	eme_NonCashIncomeExpenseFromContingentConsiderationArrangements
Namespace Prefix:	eme_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration