Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator
Income from continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars)	$ 45,635	$ 29,700	$ 130,285	$ 95,492
Loss from discontinued operation, net of income taxes (in US dollars)	(611)	(3,010)	(4,087)	(17,621)
Net income attributable to EMCOR Group, Inc. (in US dollars)	$ 45,024	$ 26,690	$ 126,198	$ 77,871
Denominator
Weighted average shares outstanding used to compute basic earnings (loss) per common share (in shares)	66,714,641	67,174,848	67,062,732	67,127,149
Effect of dilutive securities-Share-based awards (in shares)	702,906	988,853	739,874	992,591
Shares used to compute diluted earnings (loss) per common share (in shares)	67,417,547	68,163,701	67,802,606	68,119,740
Basic earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.68	$ 0.44	$ 1.94	$ 1.42
From discontinued operation (in US dollars per share)	$ (0.01)	$ (0.04)	$ (0.06)	$ (0.26)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.67	$ 0.40	$ 1.88	$ 1.16
Diluted earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.68	$ 0.43	$ 1.92	$ 1.40
From discontinued operation (in US dollars per share)	$ (0.01)	$ (0.04)	$ (0.06)	$ (0.26)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.67	$ 0.39	$ 1.86	$ 1.14
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive stock options excluded from calculation of diluted earnings per share (in shares)	0	0	0	0