Significant Accounting Policies - Computation of Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
EPS numerator:
Net loss	$ (1,775)	$ (1,845)
Less: Undistributed preferred stock dividends	0	113
Premium paid on partial preferred redemption	0	(2,219)
Net loss attributable to Limbach Holdings, Inc. common stockholders	$ (1,775)	$ (3,951)
EPS denominator:
Weighted average shares outstanding – basic (in shares)	7,662,362	7,562,586
Weighted average shares outstanding – diluted (in shares)	7,662,362	7,562,586
Net loss per share attributable to Limbach Holdings, Inc. common stockholders:
Basic (usd per share)	$ (0.23)	$ (0.52)
Diluted (usd per share)	$ (0.23)	$ (0.52)