Earnings Per Share (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
Earnings Per Share [Abstract]
Income from continuing operations attributable to EMCOR Group, Inc. common stockholders (in US dollars)									$ 172,346	$ 173,354	$ 146,861
Loss from discontinued operation, net of income taxes (in US dollars)									(60)	(4,690)	(23,069)
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
Weighted average shares outstanding used to compute basic earnings (loss) per common share (in shares)									62,789,120	66,331,886	67,086,299
Effect of dilutive securities-Share-based awards (in shares)									518,392	730,623	990,542
Shares used to compute diluted earnings (loss) per common share (in shares)									63,307,512	67,062,509	68,076,841
From continuing operations attributable to EMCOR Group, Inc. common stockholders (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
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
From continuing operations attributable to EMCOR Group, Inc. common stockholders (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
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