Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Stock Split. On May 3, 2017, our Board of Directors declared a two-for-one stock split of our issued common stock. The stock split was effected on May 26, 2017 in the form of a stock dividend. Stockholders of record at the close of business on May 15, 2017 were issued one additional share of common stock for each share of common stock owned on that date. Information pertaining to shares, per share amounts and stock-based compensation has been retroactively adjusted in the accompanying financial statements and related footnotes to reflect this stock split for the applicable periods presented prior to the stock split, except for the Consolidated Statements of Stockholders' Equity other than as noted therein. Stockholders’ equity reflects the stock split in 2017 by reclassifying from paid-in capital to common stock an amount equal to the par value of the additional shares issued as a result of the stock split. Basis of Presentation. The consolidated financial statements include the accounts of Silgan and our subsidiaries. Newly acquired subsidiaries have been included in the consolidated financial statements from their dates of acquisition. All significant intercompany transactions have been eliminated. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results may differ from those estimates.
Foreign Currency Transactions and Translations Policy	Generally, our subsidiaries that operate outside the United States use their local currency as the functional currency. The principal functional currency for our foreign operations is the Euro. Balance sheet accounts of our foreign subsidiaries are translated at exchange rates in effect at the balance sheet date, while revenue and expense accounts are translated at average rates prevailing during the year. Translation adjustments are reported as a component of accumulated other comprehensive loss. Gains or losses resulting from operating transactions denominated in foreign currencies that are not designated as a hedge are generally included in selling, general and administrative expenses in our Consolidated Statements of Income.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash equivalents represent short-term, highly liquid investments which are readily convertible to cash and have maturities of three months or less at the time of purchase. As a result of our cash management system, checks issued for payment may create negative book balances. Checks outstanding in excess of related book balances are included in trade accounts payable in our Consolidated Balance Sheets. Changes in outstanding checks are included in financing activities in our Consolidated Statements of Cash Flows to treat them as, in substance, cash advances.
Inventories	Inventories. Inventories are valued at the lower of cost or market (net realizable value). Cost for domestic inventories for our metal container business and certain portions of our closures business is principally determined on the last-in, first-out basis, or LIFO. Cost for inventories for our plastic container business and certain portions of our closures business is principally determined on the first-in, first-out basis, or FIFO. Cost for foreign inventories for our metal container business and certain portions of our closures business is principally determined on the average cost method.
Property, Plant and Equipment, Net	Property, Plant and Equipment, Net. Property, plant and equipment, net is stated at historical cost less accumulated depreciation. Major renewals and betterments that extend the life of an asset are capitalized and repairs and maintenance expenditures are charged to expense as incurred. Design and development costs for molds, dies and other tools that we do not own and that will be used to produce products that will be sold under long-term supply arrangements are capitalized. Depreciation is computed using the straight-line method over the estimated useful lives of depreciable assets. The principal estimated useful lives are 35 years for buildings and range between 3 years to 20 years for machinery and equipment. Leasehold improvements are amortized over the shorter of the life of the related asset or the life of the lease.
Goodwill and Other Intangible Assets, Net	Goodwill and Other Intangible Assets, Net. We review goodwill and other indefinite-lived intangible assets for impairment as of July 1 of each year and more frequently if circumstances indicate a possible impairment. We determined that goodwill and other indefinite-lived intangible assets were not impaired in our annual assessment performed during the third quarter. Definite-lived intangible assets are amortized over their estimated useful lives on a straight-line basis. Customer relationships have a weighted average life of approximately 20 years. Other definite-lived intangible assets consist primarily of a trade name and technology know-how and have a weighted average life of approximately 7 years.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets. We assess long-lived assets, including intangible assets with definite lives, for impairment whenever events or changes in circumstances indicate the carrying amount of the assets may not be fully recoverable. An impairment exists if the estimate of future undiscounted cash flows generated by the assets is less than the carrying value of the assets. If impairment is determined to exist, any related impairment loss is then measured by comparing the fair value of the assets to their carrying amount.
Hedging Instruments	Hedging Instruments. All derivative financial instruments are recorded in the Consolidated Balance Sheets at their fair values. Changes in fair values of derivatives are recorded in each period in earnings or other comprehensive loss, depending on whether a derivative is designated as part of a qualifying hedge transaction and, if it is, the type of hedge transaction. We utilize certain derivative financial instruments to manage a portion of our interest rate and natural gas cost exposures. We do not engage in trading or other speculative uses of these financial instruments. For a financial instrument to qualify as a hedge, we must be exposed to interest rate or price risk, and the financial instrument must reduce the exposure and be designated as a hedge. Financial instruments qualifying for hedge accounting must maintain a high correlation between the hedging instrument and the item being hedged, both at inception and throughout the hedged period. We utilize certain internal hedging strategies to minimize our foreign currency exchange rate risk. Net investment hedges that qualify for hedge accounting result in the recognition of foreign currency gains or losses, net of tax, in accumulated other comprehensive loss. We generally do not utilize external derivative financial instruments to manage our foreign currency exchange rate risk.
Income Taxes	Income Taxes. We account for income taxes using the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment of such change. No provision is made for U.S. income taxes applicable to undistributed earnings of foreign subsidiaries that are indefinitely reinvested.
Revenue Recognition	Revenue Recognition. Our revenues are primarily derived from the sale of rigid packaging products to customers. We recognize revenue at the amount we expect to be entitled to in exchange for promised goods for which we have transferred control to customers. If the consideration agreed to in a contract includes a variable amount, we estimate the amount of consideration we expect to be entitled to in exchange for transferring the promised goods to the customer. Generally, revenue is recognized at a point in time for standard promised goods at the time of shipment when title and risk of loss pass to the customer, and revenue is recognized over time in cases where we produce promised goods with no alternative use to us and for which we have an enforceable right of payment for production completed. The production cycle for customer contracts subject to over time recognition is generally completed in less than one month. Due to the short-term duration of our production cycle, we have elected the practical expedient permitting us to exclude disclosure regarding our performance obligations with respect to outstanding purchase orders. We have elected to treat shipping and handling costs after the control of goods have been transferred to the customer as a fulfillment cost. Sales and similar taxes that are imposed on our sales and collected from customers are excluded from revenues.
Stock-Based Compensation	Stock-Based Compensation. We currently have one stock-based compensation plan in effect under which we have issued stock options and restricted stock units to our officers, other key employees and outside directors. A restricted stock unit represents the right to receive one share of our common stock at a future date. Unvested restricted stock units that have been issued do not have voting rights and may not be disposed of or transferred during the vesting period.
New Accounting Pronouncements	Recently Adopted Accounting Pronouncements. In May 2014, the Financial Accounting Standards Board, or FASB, issued an accounting standards update, or ASU, that amends the guidance for revenue recognition. This amendment contains principles that require an entity to recognize revenue to depict the transfer of promised goods and services to customers at an amount that an entity expects to be entitled to in exchange for those promised goods or services. We adopted this amendment on January 1, 2018, using the modified retrospective method for all contracts for which performance was not completed as of January 1, 2018. Results for the reporting period beginning January 1, 2018 are presented under the new guidance, while prior period amounts are not adjusted. The adoption of this amendment required us to accelerate the recognition of revenue prior to shipment to certain customers in cases where we produce promised goods with no alternative use to us and for which we have an enforceable right of payment for production completed. As a result of the adoption of this amendment, we increased retained earnings by $9.1 million as of January 1, 2018. The adoption of this amendment did not have a material impact on our financial position, results of operations or cash flows. See Note 2 for further information. In March 2017, the FASB issued an ASU that amends the presentation of net periodic pension cost and net periodic postretirement benefit cost. This amendment requires an entity to disaggregate the service cost component from the other components of net periodic benefit cost, to report the service cost component in the same line item as other compensation costs and to report the other components of net periodic benefit cost (which include interest cost, expected return on plan assets, amortization of prior service cost or credit and actuarial gains and losses) separately. In addition, capitalization of net periodic benefit cost in assets is limited to the service cost component. We have adopted this amendment as of January 1, 2018. As a result of separately reporting the other components of net periodic benefit cost, we retrospectively increased cost of goods sold by $26.6 million, increased selling, general and administrative expenses by $6.8 million and reported other pension and postretirement income of $33.4 million in our Consolidated Statements of Income for the year ended December 31, 2017, based on amounts previously included in net periodic benefit costs for retirement benefits as disclosed in Note 12. The adoption of this amendment did not have a material impact on our financial position, results of operations or cash flows. In February 2016, the FASB issued an ASU that amends existing guidance for certain leases by lessees. This amendment required us to recognize assets and liabilities on the balance sheet for the rights and obligations created by long-term leases and to disclose additional quantitative and qualitative information about leasing arrangements. We adopted this amendment on January 1, 2019, using the transition method which allowed us to recognize the effects of applying this amendment as a cumulative effect to retained earnings as of January 1, 2019. We elected certain practical expedients permitted under the transition guidance for this amendment, which did not require us to reassess whether other contracts contain leases and allowed us to carryforward our lease classifications determined under the previous guidance. In addition, we elected to retain our previously determined assumptions concerning options to extend or terminate our leases. As a result of the adoption of this amendment, we recognized additional long-term assets of $160.8 million, additional related lease liabilities of $161.4 million and reduced retained earnings by $0.6 million all on January 1, 2019. The adoption of this amendment did not have a material impact on our results of operations or cash flows. See Note 2 for further information. Recently Issued Accounting Pronouncements. In June 2016, the FASB issued an ASU that amends the guidance on the accounting for credit losses on financial instruments. This new standard introduces an approach, based on expected losses, to estimate credit losses on certain types of financial instruments. The new approach to estimating credit losses (referred to as the current expected credit losses model) applies to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables. This new standard is effective for the Company on January 1, 2020. We do not expect that this new standard will have a material impact on our financial position, results of operations or cash flows.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Stock Split. On May 3, 2017, our Board of Directors declared a two-for-one stock split of our issued common stock. The stock split was effected on May 26, 2017 in the form of a stock dividend. Stockholders of record at the close of business on May 15, 2017 were issued one additional share of common stock for each share of common stock owned on that date. Information pertaining to shares, per share amounts and stock-based compensation has been retroactively adjusted in the accompanying financial statements and related footnotes to reflect this stock split for the applicable periods presented prior to the stock split, except for the Consolidated Statements of Stockholders' Equity other than as noted therein. Stockholders’ equity reflects the stock split in 2017 by reclassifying from paid-in capital to common stock an amount equal to the par value of the additional shares issued as a result of the stock split.

Basis of Presentation. The consolidated financial statements include the accounts of Silgan and our subsidiaries. Newly acquired subsidiaries have been included in the consolidated financial statements from their dates of acquisition. All significant intercompany transactions have been eliminated. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results may differ from those estimates.

Foreign Currency Transactions and Translations Policy

Generally, our subsidiaries that operate outside the United States use their local currency as the functional currency. The principal functional currency for our foreign operations is the Euro. Balance sheet accounts of our foreign subsidiaries are translated at exchange rates in effect at the balance sheet date, while revenue and expense accounts are translated at average rates prevailing during the year. Translation adjustments are reported as a component of accumulated other comprehensive loss. Gains or losses resulting from operating transactions denominated in foreign currencies that are not designated as a hedge are generally included in selling, general and administrative expenses in our Consolidated Statements of Income.

Cash and Cash Equivalents

Cash and Cash Equivalents. Cash equivalents represent short-term, highly liquid investments which are readily convertible to cash and have maturities of three months or less at the time of purchase. As a result of our cash management system, checks issued for payment may create negative book balances. Checks outstanding in excess of related book balances are included in trade accounts payable in our Consolidated Balance Sheets. Changes in outstanding checks are included in financing activities in our Consolidated Statements of Cash Flows to treat them as, in substance, cash advances.

Inventories

Inventories. Inventories are valued at the lower of cost or market (net realizable value). Cost for domestic inventories for our metal container business and certain portions of our closures business is principally determined on the last-in, first-out basis, or LIFO. Cost for inventories for our plastic container business and certain portions of our closures business is principally determined on the first-in, first-out basis, or FIFO. Cost for foreign inventories for our metal container business and certain portions of our closures business is principally determined on the average cost method.

Property, Plant and Equipment, Net

Property, Plant and Equipment, Net. Property, plant and equipment, net is stated at historical cost less accumulated depreciation. Major renewals and betterments that extend the life of an asset are capitalized and repairs and maintenance expenditures are charged to expense as incurred. Design and development costs for molds, dies and other tools that we do not own and that will be used to produce products that will be sold under

long-term supply arrangements are capitalized. Depreciation is computed using the straight-line method over the estimated useful lives of depreciable assets. The principal estimated useful lives are 35 years for buildings and range between 3 years to 20 years for machinery and equipment. Leasehold improvements are amortized over the shorter of the life of the related asset or the life of the lease.

Goodwill and Other Intangible Assets, Net

Goodwill and Other Intangible Assets, Net. We review goodwill and other indefinite-lived intangible assets for impairment as of July 1 of each year and more frequently if circumstances indicate a possible impairment. We determined that goodwill and other indefinite-lived intangible assets were not impaired in our annual assessment performed during the third quarter. Definite-lived intangible assets are amortized over their estimated useful lives on a straight-line basis. Customer relationships have a weighted average life of approximately 20 years. Other definite-lived intangible assets consist primarily of a trade name and technology know-how and have a weighted average life of approximately 7 years.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets. We assess long-lived assets, including intangible assets with definite lives, for impairment whenever events or changes in circumstances indicate the carrying amount of the assets may not be fully recoverable. An impairment exists if the estimate of future undiscounted cash flows generated by the assets is less than the carrying value of the assets. If impairment is determined to exist, any related impairment loss is then measured by comparing the fair value of the assets to their carrying amount.

Hedging Instruments

Hedging Instruments. All derivative financial instruments are recorded in the Consolidated Balance Sheets at their fair values. Changes in fair values of derivatives are recorded in each period in earnings or other comprehensive loss, depending on whether a derivative is designated as part of a qualifying hedge transaction and, if it is, the type of hedge transaction.

We utilize certain derivative financial instruments to manage a portion of our interest rate and natural gas cost exposures. We do not engage in trading or other speculative uses of these financial instruments. For a financial instrument to qualify as a hedge, we must be exposed to interest rate or price risk, and the financial instrument must reduce the exposure and be designated as a hedge. Financial instruments qualifying for hedge accounting must maintain a high correlation between the hedging instrument and the item being hedged, both at inception and throughout the hedged period.

We utilize certain internal hedging strategies to minimize our foreign currency exchange rate risk. Net investment hedges that qualify for hedge accounting result in the recognition of foreign currency gains or losses, net of tax, in accumulated other comprehensive loss. We generally do not utilize external derivative financial instruments to manage our foreign currency exchange rate risk.

Income Taxes

Income Taxes. We account for income taxes using the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment of such change. No provision is made for U.S. income taxes applicable to undistributed earnings of foreign subsidiaries that are indefinitely reinvested.

Revenue Recognition

Revenue Recognition. Our revenues are primarily derived from the sale of rigid packaging products to customers. We recognize revenue at the amount we expect to be entitled to in exchange for promised goods for which we have transferred control to customers. If the consideration agreed to in a contract includes a variable amount, we estimate the amount of consideration we expect to be entitled to in exchange for transferring the promised goods to the customer. Generally, revenue is recognized at a point in time for standard promised goods at the time of shipment when title and risk of loss pass to the customer, and revenue is recognized over time in cases where we produce promised goods with no alternative use to us and for which we have an enforceable right of payment for production completed. The production cycle for customer contracts subject to over time recognition is generally completed in less than one month. Due to the short-term duration of our production cycle, we have elected the practical expedient permitting us to exclude disclosure regarding our performance obligations with respect to outstanding purchase orders. We have elected to treat shipping and handling costs after the control of goods have been transferred to the customer as a fulfillment cost. Sales and similar taxes that are imposed on our sales and collected from customers are excluded from revenues.

Stock-Based Compensation

Stock-Based Compensation. We currently have one stock-based compensation plan in effect under which we have issued stock options and restricted stock units to our officers, other key employees and outside directors. A restricted stock unit represents the right to receive one share of our common stock at a future date. Unvested restricted stock units that have been issued do not have voting rights and may not be disposed of or transferred during the vesting period.

New Accounting Pronouncements

Recently Adopted Accounting Pronouncements. In May 2014, the Financial Accounting Standards Board, or FASB, issued an accounting standards update, or ASU, that amends the guidance for revenue recognition. This amendment contains principles that require an entity to recognize revenue to depict the transfer of promised goods and services to customers at an amount that an entity expects to be entitled to in exchange for those promised goods or services. We adopted this amendment on January 1, 2018, using the modified retrospective method for all contracts for which performance was not completed as of January 1, 2018. Results for the reporting period beginning January 1, 2018 are presented under the new guidance, while prior period amounts are not adjusted. The adoption of this amendment required us to accelerate the recognition of revenue prior to shipment to certain customers in cases where we produce promised goods with no alternative use to us and for which we have an enforceable right of payment for production completed. As a result of the adoption of this amendment, we increased retained earnings by $9.1 million as of January 1, 2018. The adoption of this amendment did not have a material impact on our financial position, results of operations or cash flows. See Note 2 for further information.

In March 2017, the FASB issued an ASU that amends the presentation of net periodic pension cost and net periodic postretirement benefit cost. This amendment requires an entity to disaggregate the service cost component from the other components of net periodic benefit cost, to report the service cost component in the same line item as other compensation costs and to report the other components of net periodic benefit cost (which include interest cost, expected return on plan assets, amortization of prior service cost or credit and actuarial gains and losses) separately. In addition, capitalization of net periodic benefit cost in assets is limited to the service cost component. We have adopted this amendment as of January 1, 2018. As a result of separately reporting the other components of net periodic benefit cost, we retrospectively increased cost of goods sold by $26.6 million, increased selling, general and administrative expenses by $6.8 million and reported other pension and postretirement income of $33.4 million in our Consolidated Statements of Income for the year ended December 31, 2017, based on amounts previously included in net periodic benefit costs for retirement benefits as disclosed in Note 12. The adoption of this amendment did not have a material impact on our financial position, results of operations or cash flows.

In February 2016, the FASB issued an ASU that amends existing guidance for certain leases by lessees. This amendment required us to recognize assets and liabilities on the balance sheet for the rights and obligations created by long-term leases and to disclose additional quantitative and qualitative information about leasing arrangements. We adopted this amendment on January 1, 2019, using the transition method which allowed us to recognize the effects of applying this amendment as a cumulative effect to retained earnings as of January 1, 2019. We elected certain practical expedients permitted under the transition guidance for this amendment, which did not require us to reassess whether other contracts contain leases and allowed us to carryforward our lease classifications determined under the previous guidance. In addition, we elected to retain our previously determined assumptions concerning options to extend or terminate our leases. As a result of the adoption of this amendment, we recognized additional long-term assets of $160.8 million, additional related lease liabilities of $161.4 million and reduced retained earnings by $0.6 million all on January 1, 2019. The adoption of this amendment did not have a material impact on our results of operations or cash flows. See Note 2 for further information.

Recently Issued Accounting Pronouncements. In June 2016, the FASB issued an ASU that amends the guidance on the accounting for credit losses on financial instruments. This new standard introduces an approach, based on expected losses, to estimate credit losses on certain types of financial instruments. The new approach to estimating credit losses (referred to as the current expected credit losses model) applies to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables. This new standard is effective for the Company on January 1, 2020. We do not expect that this new standard will have a material impact on our financial position, results of operations or cash flows.