Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of consolidation	Principles of consolidation — The Consolidated Financial Statements include the accounts of Lydall, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated.
Estimates and assumptions	Estimates and assumptions — The preparation of the Company’s Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the financial statement dates and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.
Risks and uncertainties	Risks and uncertainties — Worldwide economic cycles and political changes affect the markets that the Company’s businesses serve and affect demand for Lydall’s products and impact profitability. Among other factors, disruptions in the global credit and financial markets, including diminished liquidity and credit availability, changes in international trade agreements, swings in consumer confidence and spending, unstable economic growth and fluctuations in unemployment rates has caused economic instability and can have a negative impact on the Company’s results of operations, financial condition and liquidity.
Cash and cash equivalents	Cash and cash equivalents — Cash and cash equivalents include cash on hand and highly liquid investments with original maturities of three months or less at the date of purchase.
Concentration of credit risk	Concentrations of credit risk — Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and trade accounts receivable. The Company places its cash and cash equivalents in high-quality financial institutions. Concentrations of credit risk with respect to trade accounts receivable are limited by the large number of customers comprising the Company’s customer base and their dispersion across many different industries and geographies.
Inventories	Inventories — Inventories are valued at lower of cost or net realizable value, cost being determined using the first-in, first-out (FIFO) cost method. Inventories in excess of requirements for current or anticipated orders have been written down to net realizable value.
Pre-production design and development costs	Pre-production design and development costs — The Company enters into contractual agreements with certain customers to design and develop molds, dies and tools (collectively, “tooling”). All such tooling contracts relate to parts that the Company will supply to customers under long-term supply agreements. Tooling costs are accumulated in work-in process inventory and are charged to operations as the related revenue from the tooling is recognized. With the adoption of ASC 606, Revenue from Contracts with Customers on January 1, 2018, the Company’s revenue recognition policies require the Company to make significant judgments and estimates regarding timing of recognition based on timing of the transfer of control to the customer. The Company analyzes several factors, including but not limited to, the nature of the products being sold and contractual terms and conditions in contracts with customers to help the Company make such judgments about revenue recognition. For tooling revenue recognized over time, the Company's significant judgments include, but are not limited to, estimated costs to completion, costs incurred to date, and assessments of risks related to changes in estimates of revenues and costs. The Company's management must make assumptions regarding the work required to fulfill the performance obligations, which is dependent upon the execution by the Company's subcontractors, among other variables and contract requirements. Periodically, the Company enters into contractually guaranteed reimbursement arrangements as a mechanism to collect amounts due from customers from tooling sales. Under these arrangements, amounts due from tooling sales are collected as parts are delivered over the part supply arrangement, in accordance with the specific terms of the arrangement. The amounts due from the customer in such transactions are recorded in “Prepaid expenses and other current assets” or “Other assets, net” based upon the expected term of the reimbursement arrangement.
Property, plant and equipment	Property, plant and equipment — Property, plant, and equipment are stated at cost. Assets held under capital leases are recorded at the lower of the net present value of the minimum lease payments or the fair value of the leased asset at the inception of the lease. Property, plant and equipment, including property, plant and equipment under capital leases, are depreciated over their estimated useful lives using the straight-line method. Leasehold improvements are depreciated on a straight-line basis over the term of the lease or the life of the asset, whichever is shorter. The cost and accumulated depreciation amounts applicable to assets sold or otherwise disposed of are removed from the asset and accumulated depreciation accounts and any net gain or loss is included in the Consolidated Statements of Operations. Expenses for maintenance and repairs are charged to expense as incurred.
Goodwill and other intangible assets	Goodwill and other intangible assets — Goodwill represents costs in excess of fair values assigned to the underlying net assets of acquired companies. Goodwill and other intangible assets with indefinite lives are not amortized but are subject to annual impairment tests. All other intangible assets are amortized over their estimated useful lives, which range from 3 to 17 years. In performing impairment tests, the Company considers discounted cash flows and other market factors as best evidence of fair value. There are inherent uncertainties and management judgment required in these analyses.
Valuation of long-lived assets	Valuation of long-lived assets — The Company evaluates the recoverability of long-lived assets, or asset groups, whenever events or changes in circumstances indicate that carrying amounts may not be recoverable. Should such evaluations indicate that the related future undiscounted cash flows are not sufficient to recover the carrying values of the assets, such carrying values would be reduced to fair value and this adjusted carrying value would become the assets’ new cost basis. For long-lived assets held for sale, assets are written down to fair value, less costs to sell. Fair value is determined primarily using future anticipated cash flows that are directly associated with, and that are expected to arise as a direct result of the use and eventual disposition of the asset, or asset group, as well as market conditions and other factors. There are inherent uncertainties and management judgment required in these analyses.
Contingencies and environmental obligations	Contingencies and environmental obligations — The Company makes judgments and estimates in accordance with applicable accounting rules when it establishes reserves for legal proceedings, claims, investigations, environmental obligations and other contingent matters. Provisions for such matters are charged to expense when it is probable that a liability has been incurred and reasonable estimates of the liability can be made. Estimates of environmental liabilities are based on a variety of matters, including, but not limited to, the stage of investigation, the stage of the remedial design, evaluation of existing remediation technologies, and presently enacted laws and regulations. The amount and timing of all future expenses related to legal proceedings, claims, investigations, environmental obligations and other contingent matters may vary significantly from estimates.
Employer sponsored benefit plans	Employer sponsored benefit plans — The Company recognizes the funded status of its defined benefit pension plans and post-retirement plans. Net benefit obligations are calculated based on actuarial valuations using key assumptions related to discount rates, mortality rates and expected return on plan assets.
Derivative instruments	Derivative instruments — Derivative instruments are measured at fair value and recognized as either assets or liabilities on the Consolidated Balance Sheet in either current or non-current other assets or other accrued liabilities or other long-term liabilities depending upon maturity and commitment. For derivative instruments that are designated and qualify as a fair value hedge, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in the Consolidated Statement of Operations. For derivative instruments that are designated and qualify as a cash flow hedge, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income and reclassified into earnings in the same period or periods in which the hedge transaction affects earnings. The Company selectively uses financial instruments to manage market risk associated with exposure to fluctuations in interest rates and foreign currency rates. These financial exposures are monitored and managed by the Company as an integral part of its risk management program. The Company does not engage in derivative instruments for speculative or trading purposes. Lydall has historically not been a party to a significant number of derivative instruments.
Revenue recognition	Revenue recognition — As of January 1, 2018, the Company accounts for revenue in accordance with ASC 606, Revenue from Contracts from Customers. The Company's revenues are generated from the design and manufacture of specialty engineered filtration media, industrial thermal insulating solutions, automotive thermal and acoustical barriers for filtration/separation and thermal/acoustical applications. The Company’s revenue recognition policies require the Company to make judgments and estimates. The Company analyzes several factors, including but not limited to, the nature of the products being sold and contractual terms and conditions in contracts with customers to help the Company make such judgments about revenue recognition. In applying the Company’s revenue recognition policy, determinations must be made as to when control of products passes to the Company’s customers which can be either at a point in time or over time depending on when control of the Company’s products transfers to its customers. Revenue is generally recognized at a point in time when control passes to customers upon shipment of the Company’s products and revenue is generally recognized over time when control of the Company’s products transfers to customers during the manufacturing process. If sales are recognized at a point in time, the Company’s standard sales and shipping terms are FOB shipping point, therefore, substantially all point in time revenue is recognized upon shipment. However, the Company conducts business with certain customers on FOB destination terms and in these instances point in time revenue revenue is recognized upon receipt by the customer. In circumstances when control transfers over time, revenue is recognized based on the extent of progress towards completion of the performance obligation. Due to the nature of the work required to be performed on many of the Company’s performance obligations, the estimation of total revenue and cost at completion is complex, subject to many variables and requires significant judgment. (See Note 2. “Revenue from Contracts with Customers”) Sales returns and allowances are recorded as identified or communicated by the customer and internally approved. The Company does not provide customers with general rights of return for products sold; however, in limited circumstances, the Company will allow sales returns and allowances from customers if the products sold do not conform to specifications. The Company made an accounting policy election to record shipping and handling activities occurring after control has passed to the customer to be treated as a fulfillment cost rather than as a distinct performance obligation. Shipping and handling expenses consist primarily of costs incurred to deliver products to customers and internal costs related to preparing products for shipment and are recorded as a cost of sales. Amounts billed to customers as shipping and handling are classified as revenue when services are performed.
Research and development	Research and development — Research and development costs are charged to expense as incurred and amounted to $10.6 million in 2018, $10.8 million in 2017, and $9.0 million in 2016. Research and development costs were primarily comprised of development personnel salaries, prototype material costs and testing and trials of new products.
Earnings per share	Earnings per share — Basic earnings per common share are equal to net income divided by the weighted average number of common shares outstanding during the period. Diluted earnings per common share are equal to net income divided by the weighted average number of common shares outstanding during the period, including the effect of stock options and stock awards, if such effect is dilutive.
Income taxes	Income taxes — The provision for income taxes is based upon income reported in the accompanying Consolidated Financial Statements. Deferred income taxes reflect the impact of temporary differences between the amounts of income and expense recognized for financial reporting purposes and such amounts recognized for tax purposes. In the event the Company was to determine that it would not be able to realize all or a portion of its deferred tax assets in the future, the Company would record a valuation allowance through a charge to income in the period that such determination was made. Conversely, if the Company was to determine that it would be able to realize its deferred tax assets in the future in excess of the net carrying amounts, the Company would decrease the recorded valuation allowance and record an increase to income in the period that such determination was made.
Translation of foreign currencies	Translation of foreign currencies — Assets and liabilities of foreign subsidiaries are translated at exchange rates prevailing on the balance sheet date. Revenues and expenses are translated at average exchange rates prevailing during the period. Any resulting translation gains or losses are reported in other comprehensive income (loss).
Stock options and share grants	Stock options and share grants — The Company accounts for awards of equity instruments under the fair value method of accounting and recognizes such amounts in the Consolidated Statements of Operations. The Company recognizes expense on a straight-line basis over the vesting period of the entire award and records forfeitures as they occur. The Company estimates the fair value of option grants based on the Black Scholes option-pricing model. Expected volatility and expected term are based on historical information. The calculation assumes that future volatility and expected term are not likely to materially differ from the Company’s historical stock price volatility and historical exercise data, respectively. Compensation expense for all restricted stock awards is recorded based on the market value of the stock on the grant date and recognized as expense over the vesting period of the award. Compensation expense for performance-based restricted stock is also impacted by the probability of achieving the performance targets.
Recently adopted accounting standards and recently issued accounting standards	Recently Adopted Accounting Standards Effective January 1, 2018, the Company adopted the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, “Revenue from Contracts with Customers (Topic 606)”. The amended guidance establishes a single comprehensive model for companies to use in accounting for revenue arising from contracts with customers and will supersede most of the existing revenue recognition guidance, including industry-specific guidance. The amended guidance clarifies that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying the amended guidance, an entity will (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the contract’s performance obligations; and (5) recognize revenue when (or as) the entity satisfies a performance obligation. The Company adopted the amended guidance and all related amendments using the modified retrospective approach on January 1, 2018, at which time it became effective for the Company. The Company recognized the cumulative effect of initially applying the new revenue standard to all contracts that were not completed on the date of adoption as an adjustment to the opening balance of retained earnings. (See Note 2. “Revenue from Contracts with Customers”). At the adoption date, the cumulative impact of revenue that would have been recognized over time, was $19.6 million. The impact was primarily driven by tooling net sales of $16.3 million from customer contracts within the Thermal Acoustical Solutions ("TAS") segment. The related adoption impact to retained earnings was $1.6 million, net of tax. Refer to Note 2. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2016-01, "Financial Instruments - Overall" (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities". This ASU revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. In February 2018, the FASB issued ASU 2018-03, "Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities", which clarifies various aspects of the guidance issued in ASU 2016-01. The Company adopted both ASUs effective January 1, 2018. The adoption of these ASUs did not have any impact on the Company’s consolidated financial statements and disclosures. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments", which provides guidance on eight specific cash flow classification issues. Prior to this ASU, GAAP did not include specific guidance on these eight cash flow classification issues. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements and disclosures. Effective January 1, 2018, the Company adopted the FASB issued ASU 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory” as part of the Board’s initiative to reduce complexity in accounting standards. This ASU eliminates an exception in ASC 740, which prohibits the immediate recognition of income tax consequences of intra-entity asset transfers other than inventory. This ASU requires entities to recognize the immediate current and deferred income tax effects of intra-entity asset transfers. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements and disclosures. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash", which clarifies guidance and presentation related to restricted cash in the statement of cash flows, including stating that restricted cash should be included within cash and cash equivalents on the statement of cash flows. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements and disclosures. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2017-01, "Business Combinations (Topic 805): Clarifying the Definition of a Business", which adds guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill, and consolidation. The amendments of this ASU provide a screen to determine when an integrated set of assets and activities is not a business. The Company evaluated this ASU in connection with its 2018 acquisitions and determined that they met the definition of a business. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2017-07, "Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost". This ASU requires an entity to report the service cost component of net benefit costs in the same line item(s) as other compensation costs arising from services rendered by the pertinent employees during the period. This ASU also requires the other components of net benefit cost, which includes interest costs and actual return on plan assets to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. As required for retrospective adoption,the Company reclassified net benefit costs of $0.3 million from cost of sales and $0.4 million from the selling, product development and administrative expenses to other expense, net, in the Consolidated Statement of Operations for the year ended December 31, 2016. The Company reclassified net benefit costs of $0.3 million from cost of sales and $0.5 million from the selling, product development and administrative expenses to other expense, net, in the Consolidated Statement of Operations for the year ended December 31, 2017. The adoption of this ASU had minimal impact on the Company's consolidated financial statements and disclosures for the year ended December 31, 2018. Effective January 1, 2018, the Company adopted the FASB issued ASU No. 2017-09, "Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting". This ASU requires an entity to apply modification accounting in Topic 718 when there are changes to the terms or conditions of a share-based payment award, unless the fair value, vesting conditions, and classification of the modified award are the same as the original award immediately before the original award is modified. The adoption of this ASU did not have any impact on the Company’s consolidated financial statements and disclosures. Recently Issued Accounting Standards In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)". This ASU requires entities that lease assets with lease terms of more than 12 months to recognize right-of-use assets and lease liabilities created by those leases on their balance sheets. This ASU will also require new qualitative and quantitative disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. In July 2018, the FASB amended the leasing guidance to add a transition option. The Company plans to elect the transition option to continue to apply the legacy guidance ASC 840, Leases, including disclosure requirements, in the comparative periods presented in the year of adoption. Based on the effective date, the Company will adopt the new standard effective January 1, 2019 on a modified retrospective basis and will not restate comparative periods. The Company anticipates the ASU will have a material impact on its assets and liabilities due to the addition of right-of-use assets and lease liabilities to the balance sheet; however, it does not expect the ASU to have a material impact on the Company's consolidated cash flows or results of operations. Based on the portfolio of leases as of December 31, 2018, the Company expects to recognize approximately $28.0 million to $34.0 million of operating lease right-of-use assets and lease liabilities on its consolidated balance sheets upon adoption. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASU 842 on the Company's financial statements, disclosures and impact to its internal control over financial reporting. The Company will finalize its accounting assessment and quantitative impact of the adoption during the first quarter of 2019 and the actual impact may differ from the estimate. As the Company completes its evaluation of this new standard, new information may arise that could change the Company's current understanding of the impact to leases. Additionally, the Company continues to monitor industry activities and any additional guidance provided by regulators, standards setters, or the accounting profession, and adjust the Company's assessment and implementation plans accordingly. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718) (“ASU 2018-07”). ASU 2018-07 was issued in order to expand the guidance for stock-based compensation, to include share-based payment transactions for acquiring goods and services from nonemployees. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company does not expect the adoption of the new accounting standard to have a material impact on its consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which adds, amends and removes certain disclosure requirements related to fair value measurements. Among other changes, this standard requires certain additional disclosure surrounding Level 3 assets, including changes in unrealized gains or losses in other comprehensive income and certain inputs in those measurements. ASU 2018-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Certain amended or eliminated disclosures in this standard may be adopted early, while certain additional disclosure requirements in this standard can be adopted on its effective date. In addition, certain changes in the standard require retrospective adoption, while other changes must be adopted prospectively. The Company is currently evaluating the impact of this update on its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-14, "Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20): Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans." This ASU requires entities to disclose the weighted-average interest crediting rates for cash balance plans and other plans with promised interest crediting rates. This ASU also requires entities to disclose an explanation for significant gains and losses related to changes in the benefit obligation for the period. This ASU is effective for fiscal years beginning after December 15, 2020 with early adoption permitted. The Company is currently evaluating the method and impact the adoption of ASU 2018-14 will have on the Company’s consolidated financial statements and disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40); Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The amendments in this update require implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software, and deferred over the noncancellable term of the cloud computing arrangement plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The Company is required to adopt this new guidance in the first quarter of 2020. Early adoption is permitted. The Company is currently evaluating the impact of this update on its consolidated financial statements and related disclosures.