Earnings Per Share - Summary of weighted average number of common shares used to compute basic and dilute earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income									$ 36,214	$ 31,294	$ 21,154
Less: net income (loss) attributable to noncontrolling interest									(1,476)	207	0
Net income attributable to MYR Group Inc.	$ 12,775	$ 10,355	$ 7,207	$ 7,353	$ 10,651	$ 7,957	$ 6,835	$ 5,644	$ 37,690	$ 31,087	$ 21,154
Denominator:
Weighted average common shares outstanding (in shares)									16,587	16,441	16,273
Weighted average dilutive securities (in shares)									112	144	223
Weighted average common shares outstanding, diluted (in shares)									16,699	16,585	16,496
Net income per share attributable to MYR Group Inc.:
Basic (in dollars per share)	$ 0.77	$ 0.62	$ 0.43	$ 0.45	$ 0.65	$ 0.48	$ 0.42	$ 0.35	$ 2.27	$ 1.89	$ 1.30
Diluted (in dollars per share)	$ 0.76	$ 0.62	$ 0.43	$ 0.44	$ 0.64	$ 0.48	$ 0.41	$ 0.34	$ 2.26	$ 1.87	$ 1.28