Selected Unaudited Quarterly Information - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Information [Abstract]
Revenues (in US dollars)	$ 1,777,826	$ 1,699,128	$ 1,652,585	$ 1,589,187	$ 1,714,796	$ 1,566,711	$ 1,552,919	$ 1,590,539	$ 6,718,726	$ 6,424,965	$ 6,333,527
Gross profit (in US dollars)	252,621	235,402	239,527	216,929	248,573	222,229	220,241	216,203	944,479	907,246	821,646
Impairment loss on identifiable intangible assets	0	0	0	0	1,471	0	0	0	0	1,471	0
Gain on sale of building	0	0	0	0	0	11,749	0	0	0	11,749	0
Net income attributable to EMCOR Group, Inc. (in US dollars)	$ 51,066	$ 41,522	$ 46,849	$ 32,849	$ 42,466	$ 45,024	$ 39,913	$ 41,261	$ 172,286	$ 168,664	$ 123,792
Basic EPS from continuing operations (in US dollars per share)	$ 0.81	$ 0.66	$ 0.75	$ 0.53	$ 0.67	$ 0.68	$ 0.61	$ 0.64	$ 2.74	$ 2.61	$ 2.19
Basic EPS from discontinued operation (in US dollars per share)	0.01	0.00	0.00	(0.01)	(0.01)	(0.01)	(0.02)	(0.03)	0.00	(0.07)	(0.34)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	0.82	0.66	0.75	0.52	0.66	0.67	0.59	0.61	2.74	2.54	1.85
Diluted EPS from continuing operations (in US dollars per share)	0.80	0.66	0.74	0.52	0.66	0.68	0.61	0.64	2.72	2.59	2.16
Diluted EPS from discontinued operation (in US dollars per share)	0.01	0.00	0.00	0.00	(0.01)	(0.01)	(0.02)	(0.03)	0.00	(0.07)	(0.34)
Net income attributable to EMCOR Group, Inc. common stockholders (in US dollars per share)	$ 0.81	$ 0.66	$ 0.74	$ 0.52	$ 0.65	$ 0.67	$ 0.59	$ 0.61	$ 2.72	$ 2.52	$ 1.82