Discontinued Operations Gain on withdrawal from PBOP (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]
Gain on withdrawal from postretirement benefit plan	$ 30

Gain On Withdrawal From Postretirement Benefit Plan

No definition available.

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