Subsequent Events	12 Months Ended
Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In March 2020 the World Health Organization declared coronavirus COVID-19 a global pandemic. The COVID-19 pandemic has caused significant disruption and volatility on a global scale resulting in, among other things, an economic slowdown and the possibility of an economic recession. In response to the COVID-19 outbreak, national and local governments around the world have instituted certain measures, including travel bans, prohibitions on group events and gatherings, shutdowns of certain non-essential businesses, curfews, shelter-in-place orders and recommendations to practice social distancing. The various governmental actions have been and remain applicable to Limbach's operations in different ways, often varying by state. In some instances, these orders have resulted in shutdowns of Construction and Service projects. In limited instances, project owners have chosen to shutdown work irrespective of the existence or applicability of government action. In most markets, construction is considered an essential business and Limbach continues to staff its projects and perform work. However, as Limbach's operations have been deemed essential, we have taken several measures to combat the COVID-19 downturn. The duration of these measures is unknown and may be extended, and additional measures may be necessary. Our year-end financial results do not reflect the adverse impact of the COVID-19 pandemic, as our business first experienced the impact of the COVID-19 economic slowdown at the end of our first fiscal quarter. The New England region was the only branch where all construction activity was prohibited for a period of time. However, on April 16, 2020, the mayor of Boston (where the majority of the New England region's activity is located) announced that construction would resume in May. In addition to project suspensions in the New England region, each of the Company's other branches experienced select project suspensions and were adversely impacted. In the Service segment, the branches are experiencing a slowdown in some types of work due to restrictions on building access. However, as building access returns, the branches are expecting building owners to maintain or retrofit current facilities in lieu of funding larger capital projects. As a result of the events stated above, management performed a complete reforecast of its 2020 and 2021 financial plans. We assessed a variety of factors, including but not limited to, Construction and Service projects currently being impacted or delayed, anticipated and/or announced restart dates for impacted projects by local and state governments, construction industry financial forecasts for the remainder of 2020, and the impact of certain cost-cutting measures implemented during the end of the Company's first fiscal quarter. Based on these factors we assumed a measured recovery in revenue and gross profit commencing in May and returning to normal revenue and gross profit levels in Q4 2020. However, it is difficult to identify the nature and extent of the COVID-19 impacts and fully estimate any costs associated therewith. The impacts are expected to become more defined over time and any actual cost impact is more readily discernible as projects evolve. Based on the reforecast, management projects compliance with the financial covenants associated with its credit agreements. While management has used all currently available information in its forecasts and have considered recent market data published by the FMI, the ultimate impact of the COVID-19 pandemic on our business, results of operations, financial condition and cash flows is highly uncertain, cannot be accurately predicted and is dependent on future developments, including the duration of the pandemic and the related length of its impact on the global economy, such as a lengthy or severe recession or any other negative trend in the U.S. or global economy, and any new information that may emerge concerning the COVID-19 outbreak and the actions to contain it or treat its impact. The continued impact on our business as a result of COVID-19 pandemic could result in a material adverse effect on our business, results of operations, financial condition, prospects and the trading prices of our securities in the near-term and beyond 2020. During the first quarter of 2020, we have taken several actions to combat the COVID-19 outbreak induced downturn in our business including, but not limited to, the following: Identification of projects that have been shut down and methods for seeking to preserve any contractual entitlement that may exist; Establishment of a task force to identify possible types and areas of impact from COVID-19 for both shutdown and continuing operations; Examination of the Company's productivity and potential impact on gross profit as a result of COVID-19; Implementation of the Company's pandemic response plan; Implemented furlough, work schedule reduction plans and permanent reductions in force; Suspension of all discretionary, non-essential expenditures, including by not limited to, auto allowances, deferral of rent ranging between 1 and 3 months, 10% salary reduction for a select group of Corporate and region management and cost reduction opportunities identified by our external consultant; and Continued our hiring freeze. In addition to the above actions, we have taken steps to minimize the adverse impacts of the COVID-19 pandemic on our business and to protect the safety of our employees and have instituted daily mandatory safety talks for all employees; emphasized more frequent washing of hands and tools, social distancing, wearing masks and work protocols. The Company's existing current backlog is projected to provide substantial coverage of forecasted construction revenue for one year from the date of the financial statement issuance. Our current cash balance, together with cash we expect to generate from future operations (inclusive of actions we are taking to reduce costs and spending across our organization, in response to the COVID-19 pandemic) along with borrowings available under our 2019 Refinancing Agreement and 2019 ABL Credit Agreement, is expected to be sufficient to finance our short- and long-term capital requirements (or meet working capital requirements). In addition to the future operating cash flows of the Company, along with its existing borrowing availability and access to financial markets, the Company believes it will be able to meet any working capital and future operating requirements, and capital investment forecast opportunities. If current economic conditions decline materially from information presently available or if project shutdowns extend into the fourth quarter or the first quarter of 2021, the Company could be unable to meet its financial covenants, which would cause an event of default thereby classifying its debt as current. If the lenders were to call the debt, the Company might not have the available working capital to satisfy its outstanding debt obligations. During the first quarter of 2020, the Company granted 84,500 service-based RSUs and 84,500 performance-based PRSUs to certain employees and executives, and 19,200 service-based RSUs to the Company's non-employee directors, under the Limbach Holdings, Inc. Omnibus Incentive Plan. Upon approval of the Company's stockholders on May 30, 2019, the Company adopted the Limbach Holdings, Inc. 2019 Employee Stock Purchase Plan (“the ESPP”). On January 1, 2020, the ESPP went into effect. The ESPP enables eligible employees, as defined by the ESPP, the right to purchase the Corporation's common stock through payroll deductions during consecutive subscription periods at a purchase price of 85% of the fair market value of a common share at the end of each offering period. Annual purchases by participants are limited to the number of whole shares that can be purchased by an amount equal to ten percent of the participant's compensation or $5,000, whichever is less. Each offering period of the ESPP lasts six months, commencing on January 1st and July 1st of each year. The amounts collected from participants during a subscription period are used on the exercise date to purchase full shares of common stock. Participants may withdraw from an offering before the exercise date and obtain a refund of amounts withheld through payroll deductions. Compensation cost, representing the 15% discount applied to the fair market value of common stock, is recognized on a straight-line basis over the six-month vesting period during which employees perform related services. Under the ESPP 500,000 shares are authorized to be issued.

Subsequent Events

In March 2020 the World Health Organization declared coronavirus COVID-19 a global pandemic. The COVID-19 pandemic has caused significant disruption and volatility on a global scale resulting in, among other things, an economic slowdown and the possibility of an economic recession. In response to the COVID-19 outbreak, national and local governments around the world have instituted certain measures, including travel bans, prohibitions on group events and gatherings, shutdowns of certain non-essential businesses, curfews, shelter-in-place orders and recommendations to practice social distancing. The various governmental actions have been and remain applicable to Limbach's operations in different ways, often varying by state. In some instances, these orders have resulted in shutdowns of Construction and Service projects. In limited instances, project owners have chosen to shutdown work irrespective of the existence or applicability of government action. In most markets, construction is considered an essential business and Limbach continues to staff its projects and perform work. However, as Limbach's operations have been deemed essential, we have taken several measures to combat the COVID-19 downturn. The duration of these measures is unknown and may be extended, and additional measures may be necessary. Our year-end financial results do not reflect the adverse impact of the COVID-19 pandemic, as our business first experienced the impact of the COVID-19 economic slowdown at the end of our first fiscal quarter. The New England region was the only branch where all construction activity was prohibited for a period of time. However, on April 16, 2020, the mayor of Boston (where the majority of the New England region's activity is located) announced that construction would resume in May. In addition to project suspensions in the New England region, each of the Company's other branches experienced select project suspensions and were adversely impacted. In the Service segment, the branches are experiencing a slowdown in some types of work due to restrictions on building access. However, as building access returns, the branches are expecting building owners to maintain or retrofit current facilities in lieu of funding larger capital projects.

As a result of the events stated above, management performed a complete reforecast of its 2020 and 2021 financial plans. We assessed a variety of factors, including but not limited to, Construction and Service projects currently being impacted or delayed, anticipated and/or announced restart dates for impacted projects by local and state governments, construction industry financial forecasts for the remainder of 2020, and the impact of certain cost-cutting measures implemented during the end of the Company's first fiscal quarter. Based on these factors we assumed a measured recovery in revenue and gross profit commencing in May and returning to normal revenue and gross profit levels in Q4 2020. However, it is difficult to identify the nature and extent of the COVID-19 impacts and fully estimate any costs associated therewith. The impacts are expected to become more defined over time and any actual cost impact is more readily discernible as projects evolve. Based on the reforecast, management projects compliance with the financial covenants associated with its credit agreements.

While management has used all currently available information in its forecasts and have considered recent market data published by the FMI, the ultimate impact of the COVID-19 pandemic on our business, results of operations, financial condition and cash flows is highly uncertain, cannot be accurately predicted and is dependent on future developments, including the duration of the pandemic and the related length of its impact on the global economy, such as a lengthy or severe recession or any other negative trend in the U.S. or global economy, and any new information that may emerge concerning the COVID-19 outbreak and the actions to contain it or treat its impact. The continued impact on our business as a result of COVID-19 pandemic could result in a material adverse effect on our business, results of operations, financial condition, prospects and the trading prices of our securities in the near-term and beyond 2020.

During the first quarter of 2020, we have taken several actions to combat the COVID-19 outbreak induced downturn in our business including, but not limited to, the following:

Identification of projects that have been shut down and methods for seeking to preserve any contractual entitlement that may exist;

Establishment of a task force to identify possible types and areas of impact from COVID-19 for both shutdown and continuing operations;

Examination of the Company's productivity and potential impact on gross profit as a result of COVID-19;

Implementation of the Company's pandemic response plan;

Implemented furlough, work schedule reduction plans and permanent reductions in force;

Suspension of all discretionary, non-essential expenditures, including by not limited to, auto allowances, deferral of rent ranging between 1 and 3 months, 10% salary reduction for a select group of Corporate and region management and cost reduction opportunities identified by our external consultant; and

Continued our hiring freeze.

In addition to the above actions, we have taken steps to minimize the adverse impacts of the COVID-19 pandemic on our business and to protect the safety of our employees and have instituted daily mandatory safety talks for all employees; emphasized more frequent washing of hands and tools, social distancing, wearing masks and work protocols.

The Company's existing current backlog is projected to provide substantial coverage of forecasted construction revenue for one year from the date of the financial statement issuance. Our current cash balance, together with cash we expect to generate from future operations (inclusive of actions we are taking to reduce costs and spending across our organization, in response to the COVID-19 pandemic) along with borrowings available under our 2019 Refinancing Agreement and 2019 ABL Credit Agreement, is expected to be sufficient to finance our short- and long-term capital requirements (or meet working capital requirements). In addition to the future operating cash flows of the Company, along with its existing borrowing availability and access to financial markets, the Company believes it will be able to meet any working capital and future operating requirements, and capital investment forecast opportunities. If current economic conditions decline materially from information presently available or if project shutdowns extend into the fourth quarter or the first quarter of 2021, the Company could be unable to meet its financial covenants, which would cause an event of default thereby classifying its debt as current. If the lenders were to call the debt, the Company might not have the available working capital to satisfy its outstanding debt obligations.

During the first quarter of 2020, the Company granted 84,500 service-based RSUs and 84,500 performance-based PRSUs to certain employees and executives, and 19,200 service-based RSUs to the Company's non-employee directors, under the Limbach Holdings, Inc. Omnibus Incentive Plan.

Upon approval of the Company's stockholders on May 30, 2019, the Company adopted the Limbach Holdings, Inc. 2019 Employee Stock Purchase Plan (“the ESPP”). On January 1, 2020, the ESPP went into effect. The ESPP enables eligible employees, as defined by the ESPP, the right to purchase the Corporation's common stock through payroll deductions during consecutive subscription periods at a purchase price of 85% of the fair market value of a common share at the end of each offering period. Annual purchases by participants are limited to the number of whole shares that can be purchased by an amount equal to ten percent of the participant's compensation or $5,000, whichever is less. Each offering period of the ESPP lasts six months, commencing on January 1st and July 1st of each year. The amounts collected from participants during a subscription period are used on the exercise date to purchase full shares of common stock. Participants may withdraw from an offering before the exercise date and obtain a refund of amounts withheld through payroll deductions. Compensation cost, representing the 15% discount applied to the fair market value of common stock, is recognized on a straight-line basis over the six-month vesting period during which employees perform related services. Under the ESPP 500,000 shares are authorized to be issued.