Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Financial Statement Presentation	The accompanying unaudited interim condensed consolidated financial statements of Alamo Group Inc. and its subsidiaries (the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulations S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the periods presented are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The balance sheet at December 31, 2016 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. For further information, refer to the consolidated financial statements and footnotes thereto included in the Company’s annual report on Form 10-K for the year ended December 31, 2016 (the "2016 10-K").
New Accounting Pronouncements	In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers” (Topic 606), which supersedes the revenue recognition requirements in Accounting Standards Codification ("ASC") Topic 605, “Revenue Recognition,” and most industry-specific guidance. This ASU is based on the principle that revenue is recognized to depict the transfer of 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. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. This update is effective as of January 1, 2018, with early adoption permitted as of January 1, 2017. We have completed our evaluation of the provisions of this standard and concluded that our adoption will not change the amount or timing of revenue recognized by us, nor will it affect our financial position. In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” as part of its simplification initiative. ASU 2015-11 amends existing guidance for measuring inventories. This amendment requires the Company to measure inventories recorded using the first-in, first-out method at the lower of cost and net realizable value. This amendment does not change the methodology for measuring inventories recorded using the last-in, first-out method. This amendment was effective prospectively for the Company on January 1, 2017. The adoption of the changes did not materially affect our financial position or results of our operations. In February 2016, the FASB issued ASU No. 2016-02, “Leases.” This update requires that a lessee recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. Similar to current guidance, the update continues to differentiate between finance leases and operating leases, however this distinction now primarily relates to differences in the manner of expense recognition over time and in the classification of lease payments in the statement of cash flows. The updated guidance leaves the accounting for leases by lessors largely unchanged from existing GAAP. Entities are required to use a modified retrospective adoption, with certain relief provisions, for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements when adopted. The guidance will become effective for us on January 1, 2019. The impacts that adoption of the ASU is expected to have on our consolidated financial statements and related disclosures are being evaluated. Additionally, we have not yet determined the effect of the ASU on our internal control over financial reporting or other changes in business practices and processes. In March 2016, the FASB issued ASU No. 2016-09, “Compensation-Stock Compensation,” to simplify the accounting and reporting for employee share-based payments. This amendment, among other changes, allows for a policy election such that an entity can continue to estimate forfeitures at the time of the grant or can account for forfeitures as they occur. The amendment requires a modified retrospective approach for the adoption. In addition, the amendment eliminates the requirement to reclassify excess tax benefits from operating activities to financing activities. The effect of the change on prior period has been retrospectively adjusted to make the cash flow statements comparable. The Company adopted this ASU on January 1, 2017. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses,” to improve information on credit losses for financial instruments. The ASU replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses. The ASU is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted beginning in fiscal years beginning after December 18, 2018. The Company has not yet evaluated the effect the adoption of this ASU will have on its consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments,” to address diversity in practice on certain specific cash flow issues. The ASU is effective for the Company for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company early-adopted this ASU on January 1, 2017 and the adoption did not have an effect on the consolidated financial statements. In January 2017, the FASB issued ASU 2017-04 “Intangibles - Goodwill and Other - Simplifying the Test for Goodwill Impairment” to simplify how an entity is required to test for goodwill impairment. As a result, an entity will perform its goodwill impairment test by comparing the carrying value of a reporting unit against the fair value and will record an impairment for the amount that the carrying value of a reporting unit exceeds the fair value. The ASU is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company early-adopted this ASU on January 1, 2017 and will apply the new guidance prospectively on goodwill impairment tests. In March 2017, the FASB issued ASU 2017-07 “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” to provide income statement classification guidance for components of the net benefit cost. The ASU requires entities to disaggregate the current-service-cost component from the other components of net benefit cost (the “other components”) and present it with other current compensation costs for related employees in the income statement. Furthermore, entities should present the other components elsewhere in the income statement and outside of income from operations if such a subtotal is presented. The ASU is to be adopted retrospectively and is effective for the Company for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years and may be early adopted. The Company expects that adoption will result in a reclassification of the non-service components of pension and post-retirement costs, primarily from cost of sales and selling, general and administrative expenses to other income (loss) on the consolidated statements of income. The Company’s pensions, including net periodic cost, is disclosed in Note 13 of the 2016 10-K.

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers” (Topic 606), which supersedes the revenue recognition requirements in Accounting Standards Codification ("ASC") Topic 605, “Revenue Recognition,” and most industry-specific guidance. This ASU is based on the principle that revenue is recognized to depict the transfer of 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. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. This update is effective as of January 1, 2018, with early adoption permitted as of January 1, 2017. We have completed our evaluation of the provisions of this standard and concluded that our adoption will not change the amount or timing of revenue recognized by us, nor will it affect our financial position.

In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” as part of its simplification initiative. ASU 2015-11 amends existing guidance for measuring inventories. This amendment requires the Company to measure inventories recorded using the first-in, first-out method at the lower of cost and net realizable value. This amendment does not change the methodology for measuring inventories recorded using the last-in, first-out method. This amendment was effective prospectively for the Company on January 1, 2017. The adoption of the changes did not materially affect our financial position or results of our operations.

In February 2016, the FASB issued ASU No. 2016-02, “Leases.” This update requires that a lessee recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. Similar to current guidance, the update continues to differentiate between finance leases and operating leases, however this distinction now primarily relates to differences in the manner of expense recognition over time and in the classification of lease payments in the statement of cash flows. The updated guidance leaves the accounting for leases by lessors largely unchanged from existing GAAP. Entities are required to use a modified retrospective adoption, with certain relief provisions, for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements when adopted. The guidance will become effective for us on January 1, 2019. The impacts that adoption of the ASU is expected to have on our consolidated financial statements and related disclosures are being evaluated. Additionally, we have not yet determined the effect of the ASU on our internal control over financial reporting or other changes in business practices and processes.

In March 2016, the FASB issued ASU No. 2016-09, “Compensation-Stock Compensation,” to simplify the accounting and reporting for employee share-based payments. This amendment, among other changes, allows for a policy election such that an entity can continue to estimate forfeitures at the time of the grant or can account for forfeitures as they occur. The amendment requires a modified retrospective approach for the adoption. In addition, the amendment eliminates the requirement to reclassify excess tax benefits from operating activities to financing activities. The effect of the change on prior period has been retrospectively adjusted to make the cash flow statements comparable. The Company adopted this ASU on January 1, 2017.

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses,” to improve information on credit losses for financial instruments. The ASU replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses. The ASU is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted beginning in fiscal years beginning after December 18, 2018. The Company has not yet evaluated the effect the adoption of this ASU will have on its consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments,” to address diversity in practice on certain specific cash flow issues. The ASU is effective for the Company for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company early-adopted this ASU on January 1, 2017 and the adoption did not have an effect on the consolidated financial statements.

In January 2017, the FASB issued ASU 2017-04 “Intangibles - Goodwill and Other - Simplifying the Test for Goodwill Impairment” to simplify how an entity is required to test for goodwill impairment. As a result, an entity will perform its goodwill impairment test by comparing the carrying value of a reporting unit against the fair value and will record an impairment for the amount that the carrying value of a reporting unit exceeds the fair value. The ASU is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company early-adopted this ASU on January 1, 2017 and will apply the new guidance prospectively on goodwill impairment tests.

In March 2017, the FASB issued ASU 2017-07 “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” to provide income statement classification guidance for components of the net benefit cost. The ASU requires entities to disaggregate the current-service-cost component from the other components of net benefit cost (the “other components”) and present it with other current compensation costs for related employees in the income statement. Furthermore, entities should present the other components elsewhere in the income statement and outside of income from operations if such a subtotal is presented. The ASU is to be adopted retrospectively and is effective for the Company for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years and may be early adopted. The Company expects that adoption will result in a reclassification of the non-service components of pension and post-retirement costs, primarily from cost of sales and selling, general and administrative expenses to other income (loss) on the consolidated statements of income. The Company’s pensions, including net periodic cost, is disclosed in Note 13 of the 2016 10-K.