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, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income									$ 58,759	$ 36,214	$ 31,294
Less: net income (loss) attributable to noncontrolling interest									0	(1,476)	207
Net income attributable to MYR Group	$ 18,150	$ 17,292	$ 13,385	$ 9,932	$ 12,775	$ 10,355	$ 7,207	$ 7,353	$ 58,759	$ 37,690	$ 31,087
Denominator:
Weighted average common shares outstanding (in shares)									16,684	16,587	16,441
Weighted average dilutive securities (in shares)									206	112	144
Weighted average common shares outstanding, diluted (in shares)									16,890	16,699	16,585
Net income per share attributable to MYR Group Inc.:
Basic (in dollars per share)	$ 1.09	$ 1.04	$ 0.80	$ 0.60	$ 0.77	$ 0.62	$ 0.43	$ 0.45	$ 3.52	$ 2.27	$ 1.89
Diluted (in dollars per share)	$ 1.07	$ 1.02	$ 0.80	$ 0.59	$ 0.76	$ 0.62	$ 0.43	$ 0.44	$ 3.48	$ 2.26	$ 1.87