Basis of Presentation and Principles of Consolidation (Policies)	9 Months Ended
Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated Deficit	Accumulated Deficit The Company's accounting policy is to record dividends and accretion of redeemable stock as a reduction of retained earnings. In the absence of retained earnings, the Company will charge the dividends and/or accretion of redeemable stock to Additional Paid-in Capital until depleted and will then charge the remainder to accumulated deficit. As a result of the change in tax status from "S" Corporation to "C" Corporation in the second quarter of 2019, the Company reclassified historical retained earnings for the "S" Corporation from retained earnings to Additional Paid in Capital as of the date of conversion. Subsequent changes in accumulated deficit are related to increases or decreases in the maximum redemption value of redeemable common stock.
Fiscal Periods	Fiscal Periods In October 2018, our board of directors approved a change in our annual and quarterly fiscal period ends from the last Friday on or before the calendar year or quarterly month-end to the last day of the calendar year or quarterly month-end. Accordingly, the period end for the first, second, and third quarters of fiscal 2018 and fiscal 2019 are March 30, 2018, June 29, 2018, and September 28, 2018, respectively, and March 31, 2019, June 30, 2019, and September 30, 2019, respectively. The number of days in the three- and nine-month periods ended September 28, 2018 and September 30, 2019 were 91 and 273, respectively, and 92 and 273, respectively.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual amounts could differ from those estimates. The Company’s most significant estimates and judgments involve revenue recognition with respect to the determination of the costs to complete contracts and transaction price; determination of self-insurance reserves; valuation of the Company’s fair value of common stock (for periods prior to the IPO); useful lives of property and equipment and intangible assets; calculation of allowance for doubtful accounts; valuation of deferred income tax assets and uncertain tax positions, among others. Please see “Note 2 – Summary of Significant Accounting Policies” of Notes to Consolidated Financial Statements included in the Company’s Form S-1/A filed April 29, 2019, for a discussion of the significant estimates and assumptions affecting our consolidated financial statements. Estimates of costs to complete contracts are continually evaluated as work progresses and are revised when necessary. When a change in estimate is determined to have an impact on contract profit, the Company records a positive or negative adjustment to the consolidated statement of income.
Inventory	Inventory Included in Prepaid expenses and other current assets in the Company’s consolidated balances sheets is inventory. Inventory consists of uninstalled materials received by the Company awaiting installation at our project sites and raw materials, work-in-process, and finished goods related to the manufacture of advance technology equipment. Uninstalled materials inventory and the inventory related to advance technology equipment is carried on the Company’s consolidated balance sheets at the lower of cost (which approximates average cost) or net realizable value.
Redeemable Common Stock	Redeemable Common Stock In connection with the Company’s IPO on May 8, 2019, all Employee Stock Ownership Plan (“ESOP”) shares were contingently redeemable for cash during the 180-day lock-up period which ended on November 3, 2019. During the 180-day lock-up period, the Company presented all shares held by the ESOP as temporary equity on the consolidated balance sheets as Redeemable common stock held by Employee Stock Ownership Plan (ESOP) at their redemption value. The consolidated balance sheet, to be presented in the Company’s 2019 Annual Report on Form 10-K, at December 31, 2019 will reflect the reclassification of redeemable common stock held by the ESOP from temporary equity to permanent equity as the lock-up period expires in the fourth quarter. At the conclusion of the lock-up period all shares held by the ESOP will be redeemable by participants in shares of the Company’s common stock once vesting and eligibility requirements have been met.
Leases	Leases In February 2016, the FASB issued ASU 2016-02 “Leases (Topic 842)”, which is a new standard related to leases to increase transparency and comparability among organizations by requiring the recognition of right-of-use (“ROU”) assets obtained in exchange for lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The Company elected to adopt the standard, and available practical expedients, effective January 1, 2019. These practical expedients allowed the Company to keep the lease classification assessed under the previous lease accounting standard (ASC 840) without reassessment under the new standard, and allowed all separate lease components, including non-lease components, to be accounted for as a single lease component for all existing leases prior to adoption of the new standard. Furthermore, the Company made an accounting policy election to not recognize a lease liability and ROU asset for leases with lease terms of twelve months or less. The Company adopted this new standard under the modified retrospective transition approach without adjusting comparative periods in the financial statements, as allowed under Topic 842, and implemented internal controls and key system functionality to enable the preparation of financial information on adoption. The standard had a material impact on the Company’s consolidated balance sheets but did not have an impact on the consolidated income statements. The most significant impact was the recognition of ROU assets and lease liabilities for operating leases, while accounting for finance leases remained substantially unchanged. As a result of the adoption, the Company recorded a cumulative-effect adjustment to retained earnings of $52.6 million net of deferred tax asset adjustment of $0.7 million, representing the unamortized portion of a deferred gain previously recorded as a sale-leaseback transaction associated with the sale of an office building in 2011. The Company concluded the transaction resulted in the transfer of control of the office building to the buyer-lessor at market terms and would have qualified as a sale under Topic 842 with gain recognition in the period the sale was recognized. The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease ROU assets and current and long-term operating lease liabilities in the consolidated balance sheets. Finance leases are included in other noncurrent assets, accrued expenses and other current liabilities and other long-term liabilities in the consolidated balance sheets. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, incremental borrowing rates are used based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. Lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for operating lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, which are generally accounted for separately. For certain equipment leases, such as vehicles, we account for the lease and non-lease components as a single lease component. Additionally, for certain equipment leases, we apply a portfolio approach to effectively account for the operating lease ROU assets and liabilities. The Company has operating and finance leases for corporate and project office spaces, vehicles, heavy machinery and office equipment. Our leases have remaining lease terms of one year to 10 years, some of which may include options to extend the leases for up to five years, and some of which may include options to terminate the leases up to the seventh year. As of September 30, 2019, assets recorded under finance leases were $1.8 million and accumulated depreciation associated with finance leases was $0.5 million.

Basis of Presentation and Principles of Consolidation (Policies)

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

The Company's accounting policy is to record dividends and accretion of redeemable stock as a reduction of retained earnings. In the absence of retained earnings, the Company will charge the dividends and/or accretion of redeemable stock to Additional Paid-in Capital until depleted and will then charge the remainder to accumulated deficit. As a result of the change in tax status from "S" Corporation to "C" Corporation in the second quarter of 2019, the Company reclassified historical retained earnings for the "S" Corporation from retained earnings to Additional Paid in Capital as of the date of conversion. Subsequent changes in accumulated deficit are related to increases or decreases in the maximum redemption value of redeemable common stock.

Fiscal Periods

In October 2018, our board of directors approved a change in our annual and quarterly fiscal period ends from the last Friday on or before the calendar year or quarterly month-end to the last day of the calendar year or quarterly month-end. Accordingly, the period end for the first, second, and third quarters of fiscal 2018 and fiscal 2019 are March 30, 2018, June 29, 2018, and September 28, 2018, respectively, and March 31, 2019, June 30, 2019, and September 30, 2019, respectively. The number of days in the three- and nine-month periods ended September 28, 2018 and September 30, 2019 were 91 and 273, respectively, and 92 and 273, respectively.

Use of Estimates

The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual amounts could differ from those estimates. The Company’s most significant estimates and judgments involve revenue recognition with respect to the determination of the costs to complete contracts and transaction price; determination of self-insurance reserves; valuation of the Company’s fair value of common stock (for periods prior to the IPO); useful lives of property and equipment and intangible assets; calculation of allowance for doubtful accounts; valuation of deferred income tax assets and uncertain tax positions, among others. Please see “Note 2 – Summary of Significant Accounting Policies” of Notes to Consolidated Financial Statements included in the Company’s Form S-1/A filed April 29, 2019, for a discussion of the significant estimates and assumptions affecting our consolidated financial statements. Estimates of costs to complete contracts are continually evaluated as work progresses and are revised when necessary. When a change in estimate is determined to have an impact on contract profit, the Company records a positive or negative adjustment to the consolidated statement of income.

Inventory

Included in Prepaid expenses and other current assets in the Company’s consolidated balances sheets is inventory. Inventory consists of uninstalled materials received by the Company awaiting installation at our project sites and raw materials, work-in-process, and finished goods related to the manufacture of advance technology equipment. Uninstalled materials inventory and the inventory related to advance technology equipment is carried on the Company’s consolidated balance sheets at the lower of cost (which approximates average cost) or net realizable value.

Redeemable Common Stock

In connection with the Company’s IPO on May 8, 2019, all Employee Stock Ownership Plan (“ESOP”) shares were contingently redeemable for cash during the 180-day lock-up period which ended on November 3, 2019. During the 180-day lock-up period, the Company presented all shares held by the ESOP as temporary equity on the consolidated balance sheets as Redeemable common stock held by Employee Stock Ownership Plan (ESOP) at their redemption value. The consolidated balance sheet, to be presented in the Company’s 2019 Annual Report on Form 10-K, at December 31, 2019 will reflect the reclassification of redeemable common stock held by the ESOP from temporary equity to permanent equity as the lock-up period expires in the fourth quarter. At the conclusion of the lock-up period all shares held by the ESOP will be redeemable by participants in shares of the Company’s common stock once vesting and eligibility requirements have been met.

Leases

In February 2016, the FASB issued ASU 2016-02 “Leases (Topic 842)”, which is a new standard related to leases to increase transparency and comparability among organizations by requiring the recognition of right-of-use (“ROU”) assets obtained in exchange for lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases.

The Company elected to adopt the standard, and available practical expedients, effective January 1, 2019. These practical expedients allowed the Company to keep the lease classification assessed under the previous lease accounting standard (ASC 840) without reassessment under the new standard, and allowed all separate lease components, including non-lease components, to be accounted for as a single lease component for all existing leases prior to adoption of the new standard. Furthermore, the Company made an accounting policy election to not recognize a lease liability and ROU asset for leases with lease terms of twelve months or less.

The Company adopted this new standard under the modified retrospective transition approach without adjusting comparative periods in the financial statements, as allowed under Topic 842, and implemented internal controls and key system functionality to enable the preparation of financial information on adoption.

The standard had a material impact on the Company’s consolidated balance sheets but did not have an impact on the consolidated income statements. The most significant impact was the recognition of ROU assets and lease liabilities for operating leases, while accounting for finance leases remained substantially unchanged.

As a result of the adoption, the Company recorded a cumulative-effect adjustment to retained earnings of $52.6 million net of deferred tax asset adjustment of $0.7 million, representing the unamortized portion of a deferred gain previously recorded as a sale-leaseback transaction associated with the sale of an office building in 2011. The Company concluded the transaction resulted in the transfer of control of the office building to the buyer-lessor at market terms and would have qualified as a sale under Topic 842 with gain recognition in the period the sale was recognized.

The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease ROU assets and current and long-term operating lease liabilities in the consolidated balance sheets. Finance leases are included in other noncurrent assets, accrued expenses and other current liabilities and other long-term liabilities in the consolidated balance sheets.

ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, incremental borrowing rates are used based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. Lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for operating lease payments is recognized on a straight-line basis over the lease term.

We have lease agreements with lease and non-lease components, which are generally accounted for separately. For certain equipment leases, such as vehicles, we account for the lease and non-lease components as a single lease component. Additionally, for certain equipment leases, we apply a portfolio approach to effectively account for the operating lease ROU assets and liabilities.

The Company has operating and finance leases for corporate and project office spaces, vehicles, heavy machinery and office equipment. Our leases have remaining lease terms of one year to 10 years, some of which may include options to extend the leases for up to five years, and some of which may include options to terminate the leases up to the seventh year. As of September 30, 2019, assets recorded under finance leases were $1.8 million and accumulated depreciation associated with finance leases was $0.5 million.