Contract Assets and Liabilities - Contracts in Progress (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue earned on uncompleted contracts	$ 752,564	$ 726,215
Less: Billings to date	(766,690)	(722,562)
Net underbilling (overbilling)	(14,126)	3,653
Costs in excess of billings and estimated earnings	31,894	44,315
Billings in excess of costs and estimated earnings	$ (46,020)	$ (40,662)

The amount of billings that were raised on the contracts to date during the period.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Billings in Excess of Billings and Estimated Earnings on Uncompleted Contracts

No definition available.

Name:	lmb_BillingsinExcessofBillingsandEstimatedEarningsonUncompletedContracts
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Costs in Excess of Billings and Estimated Earnings on Uncompleted Contracts

No definition available.

Name:	lmb_CostsinExcessofBillingsandEstimatedEarningsonUncompletedContracts
Namespace Prefix:	lmb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of Asset or liability for net Under Over billings on the contracts.

No definition available.

Name:	lmb_NetUnderOverbillingOnContracts
Namespace Prefix:	lmb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of revenue earned from uncompleted contracts during the period.

No definition available.

Name:	lmb_RevenueEarnedOnUncompletedContracts
Namespace Prefix:	lmb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	us-gaap_RevenueFromContractWithCustomerAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration