Background and Summary of Significant Accounting Policies (Policies)	9 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation - The Company prepares its Condensed Consolidated Financial Statements in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The Condensed Consolidated Balance Sheet as of March 31, 2019 was derived from audited financial statements included in the Annual Report on Form 10-K for the year ended March 31, 2019 (“Fiscal 2019 Form 10-K”). The accompanying unaudited Condensed Consolidated Financial Statements contain all adjustments, of a normal recurring nature, necessary to present fairly its financial position as of December 31, 2019 and the results of operations and cash flows for the three and nine months ended December 31, 2019. The interim Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements, including the notes thereto, filed in the Company’s Fiscal 2019 Form 10-K.
Principles of Consolidation	Principles of Consolidation - The Condensed Consolidated Financial Statements include the Company, its wholly-owned subsidiaries, its majority-owned subsidiaries and variable interest entities (“VIEs”) of which the Company is the primary beneficiary. The Company uses the equity method of accounting for equity investments where it exercises significant influence but does not hold a controlling financial interest. Such investments are recorded in Other assets in the Condensed Consolidated Balance Sheets and the related equity earnings from these investments are included in Equity in net loss (income) of unconsolidated affiliates in the Condensed Consolidated Statements of Operations. All intercompany balances and transactions have been eliminated in consolidation.
Recent Accounting Guidance	Recent Accounting Guidance Recently Adopted Accounting Guidance Leases - In February 2016, the Financial Accounting Standards Board (the “FASB”) issued an accounting standard update (“ASU”) which amends the guidance for leases (“ASC 842”). This standard contains principles that will require an entity to recognize most leases on the balance sheet by recording a right-of-use asset and a lease liability, unless the lease is a short-term lease that has an accounting lease term of twelve months or less. The standard also contains other changes to the current lease guidance that may result in changes to how entities determine which contractual arrangements qualify as a lease, the accounting for executory costs, such as property taxes and insurance, as well as which lease origination costs will be capitalizable. In July 2018, the FASB amended ASC 842 to provide another transition method, allowing a cumulative effect adjustment to the opening balance of retained earnings during the period of adoption. The Company adopted these standards effective April 1, 2019 using the transition method in the July 2018 ASU which does not require adjustments to comparative periods or require modified disclosures for those periods and includes transition relief practical expedients. “Note 5. Leases” for further information on the adoption of the new lease ASUs. Hedge Accounting - In August 2017, the FASB issued an ASU which expanded an entity’s ability to apply hedge accounting for non-financial and financial risk components and provided a simplified approach for fair value hedging of interest rate risk. The standard also refined how entities assess hedge effectiveness. The Company adopted this standard effective April 1, 2019. The new standard did not have an impact on the Condensed Consolidated Financial Statements. Recent Accounting Guidance Not Yet Adopted Measurement of Credit Losses - In June 2016, the FASB issued an ASU which provides amended guidance on the measurement of credit losses on financial instruments, including trade receivables. This standard requires the use of an impairment model referred to as the current expected credit loss model. This standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those years, and early adoption is permitted for fiscal years beginning after December 15, 2018. The Company is required to adopt this standard effective April 1, 2020. The Company has formed an internal stakeholder group and is currently evaluating the impact of this standard on the Condensed Consolidated Financial Statements. Except for the pronouncements described above, there have been no new accounting pronouncements issued or adopted since the filing of the Fiscal 2019 Form 10-K that have significance, or potential significance, to the Condensed Consolidated Financial Statements.
Leases	ASC 842 Adoption - The Company adopted the provisions of ASC 842 beginning on April 1, 2019 using the transition methodology in ASC 842 which does not require adjustments to comparative periods or require modified disclosures. The Company elected the transition relief practical expedient package as described in ASC 842-10-65-1. ASC 842 provides lessees with the option of electing an accounting policy, by class of underlying asset, in which the lessee may choose not to separate nonlease components from lease components. The Company elected this practical expedient for leases of certain classes of equipment, including forklifts and fleet tractors and trailers. The Company also elected the accounting policy to not recognize the right-of-use asset and lease liability for leases with an initial expected term of 12 months or less (“Short-term leases”). The adoption of ASC 842 resulted in the recording of $13.3 million of additional lease liabilities and right-of-use assets to the beginning balance of the Company’s Condensed Consolidated Balance Sheet. Infiltrator Water Technologies adopted ASC 842 on July 31, 2019 using the same methodology and policy elections taken by the Company on April 1, 2019. The Infiltrator Water Technologies adoption of ASC 842 resulted in the recording of $11.2 million of additional lease liabilities and corresponding right-of-use assets to the beginning balance of the Company’s Condensed Consolidated Balance Sheet. The adoption did not have an impact on the Company’s Condensed Consolidated Statement of Operations and Condensed Consolidated Statement of Cash Flows. Nature of the Company’s Leases - The Company has operating and finance leases for plants, yards, corporate offices, tractors, trailers and other equipment. The Company’s leases have remaining terms of less than one year to 30 years. A portion of the Company’s yard leases include an option to extend the leases for up to 5 years. The Company has included renewal options which are reasonably certain to be excised in its right-of-use assets and lease liabilities. The Company’s lease payments are generally fixed. Certain equipment leases contain residual value guarantees that create a contingent obligation on the part of the Company to compensate the lessor if the leased asset cannot be sold for an amount in excess of a specified minimum value at the conclusion of the lease term. The calculation is based on the original cost of the transportation equipment, less lease payments made, compared to a percentage of the transportation equipment’s fair market value at the time of sale. All leased units covered by this guarantee have been classified as finance leases and a corresponding finance lease obligation was recorded. Therefore, no contingent obligation is needed. For all leases with an initial expected term of more than 12 months, the Company recorded, at the adoption date of ASC 842 or lease commencement date for leases entered into after the adoption date, a lease liability, which is the lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The Company will utilize its collateralized incremental borrowing rate commensurate to the lease term as the discount rate for its leases, unless the Company can specifically determine the lessor’s implicit rate. The incremental borrowing rate for each lease is determined based on the Company’s credit rating, adjusted for the impacts of collateral, and the lease term.

Background and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Dec. 31, 2019

Basis of Presentation - The Company prepares its Condensed Consolidated Financial Statements in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The Condensed Consolidated Balance Sheet as of March 31, 2019 was derived from audited financial statements included in the Annual Report on Form 10-K for the year ended March 31, 2019 (“Fiscal 2019 Form 10-K”). The accompanying unaudited Condensed Consolidated Financial Statements contain all adjustments, of a normal recurring nature, necessary to present fairly its financial position as of December 31, 2019 and the results of operations and cash flows for the three and nine months ended December 31, 2019. The interim Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements, including the notes thereto, filed in the Company’s Fiscal 2019 Form 10-K.

Principles of Consolidation

Principles of Consolidation - The Condensed Consolidated Financial Statements include the Company, its wholly-owned subsidiaries, its majority-owned subsidiaries and variable interest entities (“VIEs”) of which the Company is the primary beneficiary. The Company uses the equity method of accounting for equity investments where it exercises significant influence but does not hold a controlling financial interest. Such investments are recorded in Other assets in the Condensed Consolidated Balance Sheets and the related equity earnings from these investments are included in Equity in net loss (income) of unconsolidated affiliates in the Condensed Consolidated Statements of Operations. All intercompany balances and transactions have been eliminated in consolidation.

Recent Accounting Guidance

Recently Adopted Accounting Guidance

Leases - In February 2016, the Financial Accounting Standards Board (the “FASB”) issued an accounting standard update (“ASU”) which amends the guidance for leases (“ASC 842”). This standard contains principles that will require an entity to recognize most leases on the balance sheet by recording a right-of-use asset and a lease liability, unless the lease is a short-term lease that has an accounting lease term of twelve

months or less. The standard also contains other changes to the current lease guidance that may result in changes to how entities determine which contractual arrangements qualify as a lease, the accounting for executory costs, such as property taxes and insurance, as well as which lease origination costs will be capitalizable. In July 2018, the FASB amended ASC 842 to provide another transition method, allowing a cumulative effect adjustment to the opening balance of retained earnings during the period of adoption. The Company adopted these standards effective April 1, 2019 using the transition method in the July 2018 ASU which does not require adjustments to comparative periods or require modified disclosures for those periods and includes transition relief practical expedients. “Note 5. Leases” for further information on the adoption of the new lease ASUs.

Hedge Accounting - In August 2017, the FASB issued an ASU which expanded an entity’s ability to apply hedge accounting for non-financial and financial risk components and provided a simplified approach for fair value hedging of interest rate risk. The standard also refined how entities assess hedge effectiveness. The Company adopted this standard effective April 1, 2019. The new standard did not have an impact on the Condensed Consolidated Financial Statements.

Recent Accounting Guidance Not Yet Adopted

Measurement of Credit Losses - In June 2016, the FASB issued an ASU which provides amended guidance on the measurement of credit losses on financial instruments, including trade receivables. This standard requires the use of an impairment model referred to as the current expected credit loss model. This standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those years, and early adoption is permitted for fiscal years beginning after December 15, 2018. The Company is required to adopt this standard effective April 1, 2020. The Company has formed an internal stakeholder group and is currently evaluating the impact of this standard on the Condensed Consolidated Financial Statements.

Except for the pronouncements described above, there have been no new accounting pronouncements issued or adopted since the filing of the Fiscal 2019 Form 10-K that have significance, or potential significance, to the Condensed Consolidated Financial Statements.

Leases

ASC 842 Adoption - The Company adopted the provisions of ASC 842 beginning on April 1, 2019 using the transition methodology in ASC 842 which does not require adjustments to comparative periods or require modified disclosures. The Company elected the transition relief practical expedient package as described in ASC 842-10-65-1. ASC 842 provides lessees with the option of electing an accounting policy, by class of underlying asset, in which the lessee may choose not to separate nonlease components from lease components. The Company elected this practical expedient for leases of certain classes of equipment, including forklifts and fleet tractors and trailers. The Company also elected the accounting policy to not recognize the right-of-use asset and lease liability for leases with an initial expected term of 12 months or less (“Short-term leases”). The adoption of ASC 842 resulted in the recording of $13.3 million of additional lease liabilities and right-of-use assets to the beginning balance of the Company’s Condensed Consolidated Balance Sheet. Infiltrator Water Technologies adopted ASC 842 on July 31, 2019 using the same methodology and policy elections taken by the Company on April 1, 2019. The Infiltrator Water Technologies adoption of ASC 842 resulted in the recording of $11.2 million of additional lease liabilities and corresponding right-of-use assets to the beginning balance of the Company’s Condensed Consolidated Balance Sheet. The adoption did not have an impact on the Company’s Condensed Consolidated Statement of Operations and Condensed Consolidated Statement of Cash Flows.

Nature of the Company’s Leases - The Company has operating and finance leases for plants, yards, corporate offices, tractors, trailers and other equipment. The Company’s leases have remaining terms of less than one year to 30 years. A portion of the Company’s yard leases include an option to extend the leases for up to 5 years. The Company has included renewal options which are reasonably certain to be excised in its right-of-use assets and lease liabilities.

The Company’s lease payments are generally fixed. Certain equipment leases contain residual value guarantees that create a contingent obligation on the part of the Company to compensate the lessor if the leased asset cannot be sold for an amount in excess of a specified minimum value at the conclusion of the lease term. The calculation is based on the original cost of the transportation equipment, less lease payments made, compared to a percentage of the transportation equipment’s fair market value at the time of sale. All leased units covered by this guarantee have been classified as finance leases and a corresponding finance lease obligation was recorded. Therefore, no contingent obligation is needed.

For all leases with an initial expected term of more than 12 months, the Company recorded, at the adoption date of ASC 842 or lease commencement date for leases entered into after the adoption date, a lease liability, which is the lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The Company will utilize its collateralized incremental borrowing rate commensurate to the lease term as the discount rate for its leases, unless the Company can specifically determine the lessor’s implicit rate. The incremental borrowing rate for each lease is determined based on the Company’s credit rating, adjusted for the impacts of collateral, and the lease term.