Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator
Income from continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars)	$ 46,963	$ 41,348	$ 80,167	$ 84,650
Loss from discontinued operation, net of income taxes (in US dollars)	(114)	(1,435)	(469)	(3,476)
Net income attributable to EMCOR Group, Inc. (in US dollars)	$ 46,849	$ 39,913	$ 79,698	$ 81,174
Denominator
Weighted average shares outstanding used to compute basic earnings (loss) per common share (in shares)	62,809,699	67,294,498	62,932,295	67,242,392
Effect of dilutive securities-Share-based awards (in shares)	520,554	705,863	536,327	758,358
Shares used to compute diluted earnings (loss) per common share (in shares)	63,330,253	68,000,361	63,468,622	68,000,750
Basic earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.75	$ 0.61	$ 1.27	$ 1.26
From discontinued operation (in US dollars per share)	0.00	(0.02)	(0.01)	(0.05)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	0.75	0.59	1.26	1.21
Diluted earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	0.74	0.61	1.26	1.24
From discontinued operation (in US dollars per share)	0.00	(0.02)	(0.01)	(0.05)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.74	$ 0.59	$ 1.25	$ 1.19
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive restricted stock units excluded from calculation of diluted earnings per share (in shares)	0	0	35,625	0