Background and Summary of Significant Accounting Policies | 1. BACKGROUND AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business - Advanced Drainage Systems, Inc. and subsidiaries (collectively referred to as “ADS” and the “Company”), incorporated in Delaware, designs, manufactures and markets high performance thermoplastic corrugated pipe and related water management products, primarily in North and South America and Europe. ADS’s broad product line includes corrugated high density polyethylene (or “HDPE”) pipe, polypropylene (or “PP”) pipe and related water management products. The Company’s fiscal year begins on April 1 and ends on March 31. Unless otherwise noted, references to “year” pertain to our fiscal year. For example, 2018 refers to fiscal 2018, which is the period from April 1, 2017 to March 31, 2018. The Company is managed based primarily on the geographies in which it operates and reports results of operations in two reportable segments. The reportable segments are Domestic and International. Principles of Consolidation - The 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 Consolidated Balance Sheets and the related equity in earnings from these investments are included in Equity in net loss of unconsolidated affiliates in the Consolidated Statements of Operations. All intercompany balances and transactions have been eliminated in consolidation. Estimates - The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingencies and liabilities at the balance sheet date and the reported amounts of revenues and expenses during the reporting period. Significant estimates include, but are not limited to, the allowance for doubtful accounts, valuation of inventory, useful lives of property, plant and equipment and amortizing intangible assets, determination of the proper accounting for leases, valuation of equity method investments, goodwill, intangible assets and other long-lived assets for impairment, accounting for stock-based compensation and the ESOP, valuation of the redeemable convertible preferred stock, determination of allowances for sales returns, rebates and discounts, determination of the valuation allowance, if any, on deferred tax assets, and reserves for uncertain tax positions. Management’s estimates and assumptions are evaluated on an ongoing basis and are based on historical experience, current conditions and available information. Management believes the accounting estimates are appropriate and reasonably determined; however, due to the inherent uncertainties in making these estimates, actual results could differ from those estimates. Receivables and Allowance for Doubtful Accounts - Receivables include trade receivables, net of an allowance for doubtful accounts, and other miscellaneous receivables. Receivables at March 31, 2018 and 2017 are as follows: (Amounts in thousands) 2018 2017 Trade receivables $ 159,291 $ 160,655 Other miscellaneous receivables 12,670 8,288 Receivables $ 171,961 $ 168,943 As of March 31, 2018 and 2017, Other miscellaneous receivables includes an insurance recoverable of approximately $3.4 million and $2.4 million, respectively, which has a corresponding liability recorded in Other accrued liabilities. Credit is extended to customers based on an evaluation of their financial condition and collateral is generally not required. The evaluation of the customer’s financial condition is performed to reduce the risk of loss. Accounts receivable are evaluated for collectability based on numerous factors, including the length of time individual receivables are past due, past transaction history with customers, their credit worthiness and the economic environment. This estimate is periodically adjusted when management becomes aware of a specific customer’s inability to meet its financial obligations (e.g., bankruptcy filing) or as a result of changes in historical collection patterns. Inventories - Inventories are stated at the lower of cost or net realizable value. The Company’s inventories are maintained on the first-in, first-out (“FIFO”) method. Costs include the cost of acquiring materials, including in-bound freight from vendors and freight incurred for the transportation of raw materials, tooling or finished goods between the Company’s manufacturing plants and its distribution centers, direct and indirect labor, factory overhead and certain corporate overhead costs related to the production of inventory. The portion of fixed manufacturing overhead that relates to capacity in excess of our normal capacity is expensed in the period in which it is incurred and is not included in inventory. Net realizable value of inventory is established with consideration given to deterioration, obsolescence, and other factors. The Company periodically evaluates the carrying value of inventories and adjustments are made whenever necessary to reduce the carrying value to net realizable value. Property, Plant and Equipment and Depreciation Method - Property, plant and equipment are recorded at cost less accumulated depreciation, with the exception of assets acquired through acquisitions, which are initially recorded at fair value. Equipment acquired under capital lease is recorded at the lower of fair market value or the present value of the future minimum lease payments. Depreciation is computed for financial reporting purposes using the straight-line method over the estimated useful lives of the related assets or the lease term, if shorter, as follows: Years Buildings and leasehold improvement 20 — 45 or the lease term if shorter Machinery and equipment 3 — 18 Costs of additions and major improvements are capitalized, whereas maintenance and repairs that do not improve or extend the life of the asset are charged to expense as incurred. When assets are retired or disposed, the cost and related accumulated depreciation are removed from the asset accounts and any resulting gain or loss is reflected in Loss on disposal of assets and costs from exit and disposal activities in our Consolidated Statements of Operations. Construction in progress is also recorded at cost and includes capitalized interest, capitalized payroll costs and related costs such as taxes and other fringe benefits. Interest capitalized was $0.6 million, $0.6 million, and $0.4 million during the fiscal years ended March 31, 2018, 2017, and 2016, respectively. Goodwill - The Company records acquisitions resulting in the consolidation of an enterprise using the acquisition method of accounting. Under this method, the Company records the assets acquired, including intangible assets that can be identified, and liabilities assumed based on their estimated fair values at the date of acquisition. The purchase price in excess of the fair value of the identifiable assets acquired and liabilities assumed is recorded as goodwill. Goodwill is reviewed annually for impairment as of March 31 or whenever events or changes in circumstances indicate the carrying value may be greater than fair value. The goodwill impairment analysis is comprised of two steps. The first step requires the comparison of the fair value of the applicable reporting unit to its respective carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets assigned to that unit, goodwill is not considered impaired and the Company is not required to perform further testing. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company must perform the second step of the impairment test in order to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of a reporting unit’s goodwill exceeds its implied fair value, then the Company would record an impairment loss equal to the difference. With respect to this testing, a reporting unit is a component of the Company for which discrete financial information is available and regularly reviewed by management. Implied fair value of goodwill is determined by considering both the income and market approach. Determining the fair value of a reporting unit is judgmental in nature and involves the use of significant estimates and assumptions. These estimates and assumptions include revenue growth rates and operating margins used to calculate projected future cash flows, risk-adjusted discount rates, future economic and market conditions, and determination of appropriate market comparables. The fair value estimates are based on assumptions management believes to be reasonable, but are inherently uncertain. For the fiscal 2018, ADS completed a quantitative fair value assessment of the International reporting unit and determined no impairment charge was required. GAAP allows entities testing goodwill for impairment the option of performing a qualitative assessment before calculating the fair value of a reporting unit for the goodwill impairment test. If the qualitative assessment is performed, an entity is no longer required to calculate the fair value of a reporting unit unless the entity determines that, based on that assessment, it is more likely than not that its fair value is less than its carrying amount. ADS completed a quantitative fair value measurement of the Domestic reporting unit in fiscal 2016. The test indicated that the fair value of the Domestic reporting unit exceeded the carrying value, indicating that no impairment existed. ADS applied the qualitative assessment to the Domestic reporting unit for the annual impairment test performed as of March 31, 2018 and 2017. For the current year test, ADS assessed various assumptions, events and circumstances that would have affected the estimated fair value of the reporting unit as compared to its March 31, 2016 quantitative fair value measurement. The results of this assessment indicated that it is not more likely than not that the reporting unit fair value is less than the reporting unit carrying value. The Company did not incur any impairment charges for goodwill in the fiscal years ended March 31, 2018, 2017, and 2016. Intangible Assets Intangible Assets — Definite-Lived - Definite-lived intangible assets are amortized using the straight-line method over their estimated useful lives, and are tested for recoverability whenever events or changes in circumstances indicate that carrying amounts of the asset group may not be recoverable. Asset groups are established primarily by determining the lowest level of cash flows available. If the estimated undiscounted future cash flows are less than the carrying amounts of such assets, an impairment loss is recognized to the extent the fair value of the asset less any costs of disposition is less than the carrying amount of the asset. Determining the fair value of these assets is judgmental in nature and involves the use of significant estimates and assumptions. Intangible Assets — Indefinite-Lived - Indefinite-lived intangible assets are tested for impairment annually as of March 31 or whenever events or changes in circumstances indicate the carrying value may be greater than fair value. Determining the fair value of these assets is judgmental in nature and involves the use of significant estimates and assumptions. The Company bases its fair value estimates on assumptions it believes to be reasonable, but that are inherently uncertain. To estimate the fair value of these indefinite-lived intangible assets, the Company uses an income approach, which utilizes a market derived rate of return to discount anticipated performance. An impairment loss is recognized when the estimated fair value of the intangible asset is less than the carrying value. GAAP allows entities testing indefinite-lived intangible assets for impairment the option of performing a qualitative assessment before calculating the fair value of the indefinite-lived intangible assets for the impairment test. If the qualitative assessment is performed, an entity is no longer required to calculate the fair value of an indefinite-lived intangible assets unless the entity determines that, based on that assessment, it is more likely than not that its fair value is less than its carrying amount. ADS completed a quantitative fair value measurement of indefinite-lived trademarks in March 31, 2016. The test indicated that the fair value of the indefinite-lived trademarks substantially exceeded the carrying value, indicating that no impairment existed. ADS applied the qualitative assessment to specific trademarks for the annual impairment test performed as of March 31, 2018 and 2017. For the current year test, ADS assessed various assumptions, events and circumstances that would have affected the estimated fair value of the reporting unit as compared to its March 31, 2016 quantitative fair value measurement. The results of this assessment indicated that it is not more likely than not that the trademarks fair value is less than the reporting unit carrying value. The Company did not incur any impairment charges for Intangible assets in the fiscal years ended March 31, 2018, 2017, and 2016. Other Assets - Other assets include investments in unconsolidated affiliates accounted for under the equity method, cash surrender value of officer life insurance on key senior management executives, capitalized software development costs, deposits, central parts, and other miscellaneous assets. In the year ended March 31, 2018, the Company discontinued offering the cash surrender value of officer life insurance, and collected proceeds of $13.6 million from the sale of the officer life insurance. The Company capitalizes development costs for internal use software. Capitalization of software development costs begins in the application development stage and ends when the asset is placed into service. The Company amortizes such costs using the straight-line method over estimated useful lives of 2 to 10 years, which is included in General and administrative expense, Selling expense or Cost of goods sold within the Consolidated Statements of Operations depending on the nature of the asset and its intended use. Central parts represent spare production equipment items which are used to replace worn or broken production equipment parts and help reduce the risk of prolonged equipment outages. The cost of central parts is amortized on a straight line basis over estimated useful lives of 5 to 10 years. The Company evaluates its investments in unconsolidated affiliates for impairment whenever events or changes in circumstances indicate that the carrying amount might not be recoverable, and recognizes an impairment loss when a decline in value below carrying value is determined to be other-than-temporary. Under these circumstances, the Company would adjust the investment down to its estimated fair value, which then becomes its new carrying value. For the fiscal years ended March 31, 2017, the Company recorded an impairment charge of $1.3 million related to its investment in the South American Joint Venture. The impairment charge is included in Equity in net loss of unconsolidated affiliates in the Consolidated Statements of Operations. Other assets as of the fiscal years ended March 31 consisted of the following: (Amounts in thousands) 2018 2017 Investments in unconsolidated affiliates $ 12,343 $ 8,986 Cash surrender value of officer life insurance — 12,028 Capitalized software development costs, net 10,195 7,980 Deposits 2,776 1,289 Central parts 2,089 1,856 Other 10,551 14,398 Total other assets $ 37,954 $ 46,537 The following table sets forth amortization expense related to Other assets in each of the fiscal years ended March 31: (Amounts in thousands) 2018 2017 2016 Capitalized software development costs $ 2,156 $ 3,372 $ 3,872 Central parts 47 54 362 Other 1,688 1,689 1,898 Leases - Leases are reviewed for capital or operating classification at their inception. The Company uses the lower of the rate implicit in the lease or its incremental borrowing rate in the assessment of lease classification and assumes the initial lease term includes cancellable and renewal periods that are reasonably assured. For leases classified as capital leases at lease inception, the Company records a capital lease asset and lease financing obligation equal to the lesser of the present value of the minimum lease payments or the fair market value of the leased asset. The capital lease asset is recorded in Property, plant and equipment, net and amortized to its expected residual value at the end of the lease term using the straight-line method, and the lease financing obligation is amortized using the effective interest method over the lease term with the rental payments being allocated to principal and interest. For leases classified as operating leases, the Company records rent expense over the useful life using the straight-line method. Foreign Currency Translation - Assets and liabilities of foreign subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars at the current rate of exchange on the last day of the reporting period. Revenues and expenses are translated at a monthly average exchange rate and equity transactions are translated using either the actual exchange rate on the day of the transaction or a monthly average historical exchange rate. For the fiscal years ended March 31, 2018, 2017, and 2016, the Company’s Accumulated other comprehensive loss (“AOCL”) consisted of foreign currency translation gains and losses. Net Sales - The Company sells pipe products and related water management products. ADS ships products to customers predominantly by internal fleet and to a lesser extent by third-party carriers. The Company does not provide any additional revenue generating services after product delivery. Sales, net of sales tax and allowances for returns, rebates and discounts are recognized from product sales when persuasive evidence of an arrangement exists, delivery has occurred, the price to the buyer is fixed or determinable and collectability is reasonably assured. ADS recognizes revenue when both persuasive evidence of an arrangement and the price is fixed or determinable. Title to the products and risk of loss generally passes to the customer upon delivery. ADS performs credit check procedures on all new customers, establishes credit limits accordingly, and monitors the creditworthiness of existing customers, which is the basis for concluding that collectability is reasonably assured. Shipping Costs - The Company incurs shipping costs to deliver products to customers using an in-house fleet or common carrier. Typically shipping costs are prepaid and included in the product price; however, in some instances, the Company bills shipping costs to customers. Shipping costs are also incurred to physically move raw materials, tooling and products between manufacturing and distribution facilities. Shipping costs for the fiscal years ended March 31, 2018, 2017, and 2016 were $133.8 million, $120.4 million, and $120.5 million, respectively, and are included in Cost of goods sold. Shipping costs billed to customers were $6.3 million, $5.5 million, and $7.0 million during 2018, 2017 and 2016, respectively, and are included in Net sales. Stock-Based Compensation - See “Note 16. Stock-Based Compensation” for information about our stock-based compensation award programs and related accounting policies. Advertising - The Company expenses advertising costs as incurred. Advertising costs are recorded in Selling expenses in the Consolidated Statements of Operations. The total advertising costs were $4.1 million, $3.1 million, and $3.2 million for the fiscal years ended March 31, 2018, 2017, and 2016, respectively. Self-Insurance - The Company is self-insured for short term disability and medical coverage it provides for substantially all eligible employees. The Company is self-insured for medical claims up to the individual and aggregate stop-loss coverage limits. The Company accrues for claims incurred but not reported based on an estimate of future claims related to events that occurred prior to the fiscal year end if it has not met the aggregate stop-loss coverage limit. Amounts expensed totaled $41.3 million, $39.5 million, and $37.5 million for the fiscal years ended March 31, 2018, 2017, and 2016, respectively, of which employees contributed $5.9 million, $5.1 million, and $4.5 million, respectively. ADS is also self-insured for various other general insurance programs to the extent of the applicable deductible limits on the Company’s insurance coverage. These programs include primarily automobile, general liability and employment practices coverage with a deductible of $0.3 million per occurrence or claim incurred. Amounts expensed during the period, including an estimate for claims incurred but not reported at year end, were $2.2 million, $1.8 million, and $2.1 million, for the years ended March 31, 2018, 2017, and 2016, respectively. ADS is also self-insured for workers’ compensation insurance with stop-loss coverage for claims that exceed $0.5 million per incident up to the respective state statutory limits. Amounts expensed, including an estimate for claims incurred but not reported, were $1.3 million, $2.1 million, and $3.9 million for the fiscal years ended March 31, 2018, 2017, and 2016, respectively. Income Taxes - Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized and represent the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. They are measured using the enacted tax rates expected to apply to taxable income in the years in which the related temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The deferred income tax provision represents the change during the reporting period in the deferred tax assets and deferred tax liabilities. Penalties and interest recorded on income taxes payable are recorded as part of Income tax expense. The Company determines whether an uncertain tax position is more likely than not to be sustained upon examination, including resolution of any related appeals or litigation process, based upon the technical merits of the position. For tax positions meeting the more likely than not threshold, the tax amount recognized in the financial statements is the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon ultimate settlement with the relevant taxing authority. Fair Values - The fair value framework requires the categorization of assets and liabilities into three levels based upon assumptions (inputs) used to price the assets or liabilities. Level 1 provides the most reliable measure of fair value, whereas Level 3 generally requires significant management judgment. The three levels are defined as follows: Level 1 — Unadjusted quoted prices in active markets for identical assets and liabilities. Level 2 — Observable inputs other than those included in Level 1. For example, quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in inactive markets. Level 3 — Unobservable inputs reflecting management’s own assumptions about the inputs used in pricing the asset or liability. ADS’s policy for determining when transfers between levels have occurred is to use the actual date of the event or change in circumstances that caused the transfer. Concentrations of Risk - The Company has a large, active customer base of approximately twenty thousand customers with two customers, Ferguson Enterprises and Core and Main, each representing more than 10% of annual net sales. Such customers accounted for 25.4%, 23.5%, and 21.1% of fiscal year 2018, 2017 and 2016 net sales, respectively. The Company’s customer base is diversified across the range of end markets that it serves. Financial instruments that potentially subject the Company to a concentration of credit risk consist principally of Receivables. The Company provides its products to customers based on an evaluation of the customers’ financial condition, generally without requiring collateral. Exposure to losses on Receivables is principally dependent on each customer’s financial condition. The Company performs ongoing credit evaluations of its customers. The Company monitors the exposure for credit losses and maintains allowances for anticipated losses. Concentrations of credit risk with respect to Receivables are limited due to the large number of customers comprising the Company’s customer base and their dispersion across many different geographies. One customer, Ferguson Enterprises, accounted for approximately 17.6% and 15.7% of Receivables at March 31, 2018 and 2017, respectively. Derivatives - The Company recognizes derivative instruments as either assets or liabilities and measure those instruments at fair value. ADS uses interest rate swaps, commodity options in the form of collars and swaps, and foreign currency forward contracts to manage various exposures to interest rate, commodity price, and exchange rate fluctuations. These instruments do not qualify for hedge accounting treatment. For the interest rate swap executed on June 28, 2017, gains and losses resulting from the difference between the spot rate and applicable base rate is recorded in Interest expense. For commodity options in the form of collars and swaps, and foreign currency forward contracts, gains and losses from contract settlements and changes in fair value of the derivative instruments are recognized in Derivative losses (gains) and other expense (income), net in the Consolidated Statements of Operations. The Company’s policy is to present all derivative balances on a gross basis. The Company also has forward purchase agreements in place with certain resin suppliers for virgin polyethylene resin. The agreements specify a fixed amount of virgin resin material to be purchased at a fixed price for a given period of time in quantities the Company will use in the normal course of business, and therefore, qualify as normal purchase contracts. The cost of such resin is recognized in Cost of goods sold in the Consolidated Statements of Operations. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements Measurement of Inventory — In July 2015, the Financial Accounting Standards Board (“FASB”) issued an accounting standards update (“ASU”) which requires entities to measure most inventory at the lower of cost and net realizable value, simplifying current guidance under which an entity must measure inventory at the lower of cost or market. The determination of market value, under current guidance, is considered unnecessarily complex as there are several potential outcomes based on its definition as replacement cost, net realizable value, or net realizable value less an approximate normal profit margin. Whereas net realizable value, under the update, is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company adopted this standard effective April 1, 2017. The new standard did not have a material impact on the Consolidated Financial Statements. Stock-Based Compensation — In March 2016, the FASB issued an ASU which is intended to simplify certain aspects of the accounting for stock-based compensation. The Company adopted the standard on April 1, 2017. The adoption of the ASU did not have a material impact on the historical Consolidated Financial Statements. This update contains changes to the accounting for excess tax benefits, whereby excess tax benefits will be recognized in the income statement rather than in additional paid-in capital on the balance sheet. This update is expected to result in increased volatility to income tax expense in future periods dependent upon the timing of employee exercises of stock options, the price of the Company's common stock and the vesting of restricted stock awards. In addition, excess tax benefits will now be classified as operating cash flows rather than financing cash flows in the Consolidated Statements of Cash Flows. The amendment also contained potential changes to the accounting for forfeitures, whereby entities could elect to either continue to apply the previous requirement to estimate forfeitures when determining compensation expense, or to alternatively reverse the compensation expense of forfeited awards when they occur. The Company will account for forfeitures as they occur, which may result in expense volatility based on the timing of forfeitures. In addition, the update also modified the net-share settlement liability classification exception for statutory income tax withholdings, whereby the new guidance allows an employer with a statutory income tax withholding obligation to withhold shares with a fair value up to the maximum statutory tax rate in the employee’s applicable jurisdiction. The Company included this provision in awards issued in fiscal 2017 and modified previously issued awards on April 1, 2017. See “Note 16. Stock-Based Compensation” for further information on the modification. Recent Accounting Pronouncements Not Yet Adopted Revenue Recognition — In May 2014, the FASB issued an accounting standards update which amends the guidance for revenue recognition. This amendment contains principles that will require an entity to recognize revenue to depict the transfer of goods and services to customers at an amount that an entity expects to be entitled to in exchange for goods or services. The amendment sets forth a new revenue recognition model that requires identifying the contract, identifying the performance obligations and recognizing the revenue upon satisfaction of performance obligations. In August 2015, the FASB issued an additional accounting standards update that deferred the effective date of the new revenue standard for public entities to periods beginning after December 15, 2017, with early adoption permitted but not earlier than the original effective date of periods beginning after December 15, 2016. There have also been various additional accounting standards updates issued by the FASB in 2016 that further amend this new revenue standard. The updated standard permits the use of either the retrospective or cumulative effect transition method. The Company will adopt this standard effective April 1, 2018 using the modified retrospective method. The adoption of this standard will result in the Company recording a contract asset for estimated inventory returns. At March 31, 2018, the estimated inventory returns would have resulted in a $0.6 million decrease in Receivables, net and a $0.6 million increase in Other current assets on the Company’s Consolidated Balance Sheets. The adoption of this standard will not cause a material shift in the amount or timing of revenue recognition. Leases — In February 2016, the FASB issued an accounting standards update which amends the guidance for leases. This amendment 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 amendment 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. The new standard also requires expanded quantitative and qualitative disclosures. This update is effective for fiscal years beginning after December 15, 2018, including interim periods within those years, and early adoption is permitted. The updated standard requires the use of the modified re |