Dividends Payable, Increase (Decrease) to Amount Per Share

No definition available.

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Namespace Prefix:	eme_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

+ Details

Name:	us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 30

-Article 5

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_EquityClassOfTreasuryStockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

+ Details

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

+ Details

Name:	us-gaap_StockRepurchasedDuringPeriodValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_ShareRepurchaseProgramAxis=eme_RepurchaseProgramDec052013Member
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- Details

Name:	us-gaap_ShareRepurchaseProgramAxis=eme_RepurchaseProgramOct232014Member
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- Details

Name:	us-gaap_ShareRepurchaseProgramAxis=eme_RepurchaseProgramSep262011Member
Namespace Prefix:
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Period Type:

Common Stock (Details) (USD $)	0 Months Ended		1 Months Ended		3 Months Ended			12 Months Ended			48 Months Ended
Common Stock (Details) (USD $)	Dec. 28, 2012	Dec. 07, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Sep. 26, 2011	Dec. 05, 2013	Oct. 23, 2014
Equity, Class of Treasury Stock [Line Items]
Common stock, outstanding (in shares)			66,896,518us-gaap_CommonStockSharesOutstanding		66,896,518us-gaap_CommonStockSharesOutstanding			62,981,229us-gaap_CommonStockSharesOutstanding	66,896,518us-gaap_CommonStockSharesOutstanding		62,981,229us-gaap_CommonStockSharesOutstanding
Special dividend declared (in dollars per share)		$ 0.25us-gaap_DividendsPayableAmountPerShare
Increase in quarterly dividend declared (in dollars per share)		$ 0.06	$ 0.08	$ 0.06
Dividend paid (in dollars per share)	$ 0.06				$ 0.06	$ 0.06	$ 0.06
Stock repurchased (in US dollars)								$ 206,028,000	$ 26,070,000	$ 23,912,000
RepurchaseProgramSept262011
Equity, Class of Treasury Stock [Line Items]
Stock repurchase, authorized amount (in US dollars)												100,000,000
Number of shares repurchased (in shares)								4,800,000			7,600,000
Stock repurchased (in US dollars)								206,000,000			283,500,000
RepurchaseProgramDec52013
Equity, Class of Treasury Stock [Line Items]
Stock repurchase, authorized amount (in US dollars)													100,000,000
RepurchaseProgramOct232014
Equity, Class of Treasury Stock [Line Items]
Stock repurchase, authorized amount (in US dollars)														250,000,000
Remaining authorized repurchase amount (in US dollars)								$ 166,500,000			$ 166,500,000