Consolidated Statements Of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 7,686,999	$ 7,551,524	$ 6,718,726
Cost of sales	6,539,987	6,513,662	5,774,247
Gross profit	1,147,012	1,037,862	944,479
Selling, general and administrative expenses	757,062	725,538	656,573
Restructuring expenses	1,577	1,438	824
Impairment loss on goodwill and identifiable intangible assets	57,819	2,428	0
Operating income	330,554	308,458	287,082
Interest expense	(12,770)	(12,627)	(8,932)
Interest income	965	663	673
Income from continuing operations before income taxes	318,749	296,494	278,823
Income tax provision	90,699	111,199	106,256
Income from continuing operations	228,050	185,295	172,567
Loss from discontinued operation, net of income taxes	(857)	(3,142)	(60)
Net income including noncontrolling interests	227,193	182,153	172,507
Less: Net loss (income) attributable to noncontrolling interests	3	(218)	(221)
Net income attributable to EMCOR Group, Inc. (in US dollars)	$ 227,196	$ 181,935	$ 172,286
Basic earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 3.85	$ 3.05	$ 2.74
From discontinued operation (in US dollars per share)	(0.01)	(0.05)	0.00
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	3.84	3.00	2.74
Diluted earnings (loss) per common share:
From continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	3.83	3.02	2.72
From discontinued operation (in US dollars per share)	(0.01)	(0.05)	0.00
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	3.82	2.97	2.72
Dividends declared per common share (in US dollars per share)	$ 0.32	$ 0.32	$ 0.32