Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Quarterly Financial Information [Line Items]
Revenues	$ 446,345		$ 399,537	$ 339,676	$ 345,611	$ 373,501		$ 373,502	$ 356,185	$ 300,129	$ 1,531,169	$ 1,403,317	$ 1,142,487
Gross profit	47,391		45,286	38,630	35,753	36,894		34,853	27,517	25,740	167,060	125,004	134,723
Net income attributable to MYR Group	$ 10,651		$ 7,957	$ 6,835	$ 5,644	$ 13,579		$ 5,145	$ 1,230	$ 1,200	$ 31,087	$ 21,154	$ 21,431
Basic earnings per share attributable to MYR Group	$ 0.65		$ 0.48	$ 0.42	$ 0.35	$ 0.83		$ 0.32	$ 0.08	$ 0.07	$ 1.89	$ 1.30	$ 1.25
Diluted earnings per share attributable to MYR Group	$ 0.64		$ 0.48	$ 0.41	$ 0.34	$ 0.82		$ 0.31	$ 0.07	$ 0.07	$ 1.87	$ 1.28	$ 1.23

[1] Results for the fourth quarter of 2017 include a net 2017 Tax Act benefit of $7.8 million, or $0.48 and $0.47 per basic and diluted share, respectively.