Earnings Per Share - Summary of weighted average number of shares outstanding (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income attributable to MYR Group Inc.	$ 17,292	$ 10,355	$ 40,609	$ 24,915
Denominator:
Weighted average common shares outstanding (in shares)	16,698	16,614	16,670	16,576
Weighted average dilutive securities (in shares)	184	100	128	116
Weighted average common shares outstanding, diluted (in shares)	16,882	16,714	16,798	16,692
Income per common share attributable to MYR Group Inc.:
Basic (in dollars per share)	$ 1.04	$ 0.62	$ 2.44	$ 1.50
Diluted (in dollars per share)	$ 1.02	$ 0.62	$ 2.42	$ 1.49