Critical and Significant Accounting (Policies)	12 Months Ended
Dec. 31, 2017
Critical and Significant Accounting Policies
Acquisitions	Acquisitions The company records acquisitions resulting in the consolidation of an enterprise using the purchase method of accounting. Under this method, the acquiring company records the assets acquired, including intangible assets that can be identified and named, 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 assets acquired and liabilities assumed is recorded as goodwill. If the assets acquired, net of liabilities assumed, are greater than the purchase price paid, then a bargain purchase has occurred and the company will recognize the gain immediately in earnings. Among other sources of relevant information, the company uses independent appraisals and actuarial or other valuations to assist in determining the estimated fair values of the assets and liabilities. Various assumptions are used in the determination of these estimated fair values including discount rates, market and volume growth rates, product selling prices, production costs and other prospective financial information. Transaction costs associated with acquisitions are expensed as incurred and included in the business consolidation and other activities line of the consolidated statement of earnings. For acquisitions where the company already owns an equity investment in the acquired company, the company will recognize in earnings, upon the completion of the acquisition, a gain or loss related to the company’s existing equity investment. This gain or loss is calculated based on the fair value of the equity investment as compared to the carrying value of the existing equity investment on the date of acquisition. When the company purchases additional interests of consolidated subsidiaries that does not result in a change in control, the difference between the fair value and carrying value of the noncontrolling interests acquired is accounted for in the common stock line within shareholders' equity.
Exit and Other Closure Costs (Business Consolidation Costs)	Exit and Other Closure Costs (Business Consolidation Costs) The company estimates its liabilities for business closure activities by accumulating detailed estimates of costs and asset sale proceeds, if any, for each business consolidation initiative. This includes the estimated costs of employee severance, pension and related benefits; impairment of property and equipment and other assets, including estimates of net realizable value; accelerated depreciation; termination payments for contracts and leases; contractual obligations; and any other qualifying costs related to the exit plan. These estimated costs are grouped by specific projects within the overall exit plan and are then monitored on a monthly basis. Such charges represent management’s best estimates, but require assumptions about the plans that may change over time. Changes in estimates for individual locations and other matters are evaluated periodically to determine if a change in estimate is required for the overall restructuring plan. Subsequent changes to the original estimates are included in current earnings and identified as business consolidation gains or losses.
Defined Benefit Pension Plans and Other Employee Benefits	Defined Benefit Pension Plans and Other Employee Benefits The company has defined benefit plans that cover a significant portion of its employees. The company also has postretirement plans that provide certain medical benefits and life insurance for retirees and eligible dependents and, to a lesser extent, participates in multi-employer defined benefit plans for which Ball is not the sponsor. For the company-sponsored plans, the relevant accounting guidance requires that management make certain assumptions relating to the long-term rate of return on plan assets, discount rates used to determine the present value of future obligations and expenses, salary inflation rates, health care cost trend rates, mortality rates and other assumptions. The company believes that the accounting estimates related to our pension and postretirement plans are critical accounting estimates because they are highly susceptible to change from period to period based on the performance of plan assets, actuarial valuations, market conditions and contracted benefit changes. The selection of assumptions is based on historical trends and known economic and market conditions at the time of valuation, as well as independent studies of trends performed by the company’s actuaries. However, actual results may differ substantially from the estimates that were based on the critical assumptions. The company recognizes the funded status of each defined benefit pension plan and other postretirement benefit plans in the consolidated balance sheet. Each overfunded plan is recognized as an asset, and each underfunded plan is recognized as a liability. Pension plan liabilities are revalued annually, or when an event occurs that requires remeasurement, based on updated assumptions and information about the individuals covered by the plan. For pension plans, accumulated actuarial gains and losses in excess of a 10 percent corridor and the prior service cost are amortized on a straight-line basis from the date recognized over the average remaining service period of active participants or over the average life expectancy for plans with significant inactive participants. For other postemployment benefits, the 10 percent corridor is not used. The majority of costs related to defined benefit and other postretirement plans are included in cost of sales; the remainder is included in selling, general and administrative expenses. In addition to defined benefit and postretirement plans, the company maintains reserves for employee medical claims, up to our insurance stop-loss limit, and workers’ compensation claims. These are regularly evaluated and revised, as needed, based on a variety of information, including historical experience, actuarial estimates and current employee statistics.
Income Taxes	Income Taxes Deferred income taxes reflect the future tax consequences of differences between the tax bases of assets and liabilities and their financial reporting amounts at each balance sheet date, based upon enacted income tax laws and tax rates. Income tax expense or benefit is provided based on earnings reported in the financial statements. The provision for income tax expense or benefit differs from the amounts of income taxes currently payable because certain items of income and expense included in the consolidated financial statements are recognized in different time periods by taxing authorities. Deferred tax assets, including operating loss, capital loss and tax credit carryforwards, are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that any portion of these tax attributes will not be realized. In addition, from time to time, management must assess the need to accrue or disclose uncertain tax positions for proposed adjustments from various federal, state and foreign tax authorities who regularly audit the company in the normal course of business. In making these assessments, management must often analyze complex tax laws of multiple jurisdictions, including many foreign jurisdictions. The accounting guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The company records the related interest expense and penalties, if any, as tax expense in the tax provision.
Derivative Financial Instruments	Derivative Financial Instruments The company uses derivative financial instruments for the purpose of hedging commercial risk exposures to fluctuations in interest rates, currency exchange rates, raw material costs, inflation rates and common share prices. The company’s derivative instruments are recorded in the consolidated balance sheets at fair value. The company values each derivative financial instrument either by using a single valuation technique based on observable market inputs performed internally or by obtaining valuation information from a reliable and observable market source. For a derivative designated as a cash flow hedge, the derivative's mark to fair value is initially recorded as a component of accumulated other comprehensive earnings and subsequently reclassified into earnings when the hedged item affects earnings, unless it is probable that the forecasted transaction will not occur. Derivatives that do not qualify for hedge accounting are marked to fair value with gains and losses immediately recorded in earnings. In the consolidated statements of cash flows, derivative activities are classified based on the cash flows of the items being hedged. Realized gains and losses from hedges are classified in the consolidated statements of earnings consistent with the accounting treatment of the items being hedged. Upon the early dedesignation of an effective derivative contract, the gains or losses are deferred in accumulated other comprehensive earnings until the originally hedged item affects earnings unless it is probable the hedged item will not occur at which time it is recognized immediately. Any gains or losses incurred after the dedesignation date are recorded in earnings immediately.
Contingencies	Contingencies The company is subject to various legal proceedings and claims, including those that arise in the ordinary course of business. The company records loss contingencies when it determines that the outcome of the future event is probable of occurring and the amount of the loss can be reasonably estimated. Gain contingencies are recognized in the financial statements when they are realized. The determination of a reserve for a loss contingency is based on management’s judgment of probability and estimates with respect to the likelihood of an outcome and valuation of the future event. Liabilities are recorded or adjusted when events or circumstances cause these judgments or estimates to change. In assessing whether a loss is probable, Ball may consider the following factors, among others: the nature of the litigation, claim or assessment; available information, opinions or views of legal counsel and other advisors; and the experience gained from similar cases by the company and others. The company provides disclosures for material contingencies when there is a reasonable possibility that a loss or an additional loss may be incurred. Actual amounts realized upon settlement of contingencies may be different than amounts recorded and disclosed, and could have a significant impact on the company's consolidated financial statements.
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation The consolidated financial statements include the accounts of Ball, its consolidated subsidiaries, and variable interest entities in which the company is considered to be the primary beneficiary. Equity investments in which the company exercises significant influence but does not control and is not the primary beneficiary are accounted for using the equity method of accounting. Investments in which the company neither exercises significant influence over the investee, nor is the primary beneficiary of the investment, are accounted for using the cost method of accounting. Intercompany transactions are eliminated in consolidation.
Inventories	Inventories Inventories are stated at the lower of cost or market using either the first-in, first-out (FIFO) cost method of accounting or the average cost method. Inventory cost is calculated for each inventory component taking into consideration the appropriate cost factors including fixed and variable overhead, material price volatility and production levels.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We review long-lived assets for impairment when circumstances indicate the carrying amount of an asset or asset group may not be recoverable based on the undiscounted future cash flows of the asset. We review long-lived assets for impairment at the individual asset or the asset group level for which the lowest level of independent cash flows can be identified. If the carrying amount of the asset or asset group is determined not to be recoverable, a write-down to fair value is recorded. Fair values are determined based on quoted market values, discounted cash flows or external appraisals, as applicable.
Depreciation and Amortization	Depreciation and Amortization Property, plant and equipment are carried at the cost of acquisition or construction and depreciated over the estimated useful lives of the assets. Repairs and maintenance costs, including labor and material costs for major improvements such as annual production line overhauls, are expensed as incurred, unless those costs substantially increase the useful lives or capacity of the existing assets. Assets are depreciated and amortized using the straight-line method over their estimated useful lives, generally 5 to 40 years for buildings and improvements and 2 to 20 years for machinery and equipment. Finite-lived intangible assets, excluding capitalized software costs, are generally amortized over their estimated useful lives of 3 to 18 years. For capitalized software, costs are generally amortized over their estimated useful lives of 3 to 7 years. The company periodically reviews these estimated useful lives and when appropriate, changes are made prospectively. For certain business consolidation activities, accelerated depreciation may be required over the revised remaining useful life for assets designated to be scrapped or abandoned. The accelerated depreciation related to such activities is disclosed as part of business consolidation and other activities in the appropriate period.
Environmental Reserves	Environmental Reserves The company estimates its liability for environmental matters based on, among other factors, the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of loss. The company records the best estimate of a loss when the loss is considered probable. As additional information becomes available, the company reassesses the potential liability related to pending matters and revises the estimates.
Revenue Recognition in the Packaging Segments	Revenue Recognition in the Packaging Segments The company recognizes sales of products in the packaging segments when the four basic criteria of revenue recognition are met: delivery has occurred, title has transferred, there is persuasive evidence of an agreement or arrangement and the price is fixed or determinable and collection is reasonably assured. Shipping and handling costs are reported within cost of sales in the consolidated statement of earnings. All revenues are presented net of tax.
Revenue Recognition in the Aerospace Segment	Revenue Recognition in the Aerospace Segment Sales under long-term contracts in the aerospace segment are primarily recognized using percentage-of-completion under the cost-to-cost method of accounting. The two primary types of long-term sales contracts utilized are cost-type contracts, which are agreements to perform for cost plus an agreed upon profit component and fixed price sales contracts, which are completed for a fixed-price. Cost-type sales contracts can have different types of fee arrangements, including fixed-fee, cost, milestone and performance incentive fees, award fees or a combination thereof. At the inception of contract performance, our estimates of base, incentive and other fees are established at a conservative estimate of profit over the period of contract performance. Throughout the period of contract performance, the company regularly reevaluates and, if necessary, revises estimates of total contract revenue, total contract cost, extent of progress toward completion, probability of receipt of any award and performance fees and any clawback provisions included in the contract. Provision for estimated contract losses, if any, is made in the period that such losses are determined to be probable. Because of sales contract payment schedules, limitations on funding and contract terms, our sales and accounts receivable generally include amounts that have been earned but not yet billed. Contract claims are only recorded if it is probable that the claim will result in additional contract revenue and the claim amounts can be reliably estimated. Revenue associated with claims is recorded only for costs already incurred and does not include a profit component. Pre-contract costs that are not approved by the customer for reimbursement are expensed as incurred. As a prime U.S. government contractor or subcontractor, the aerospace segment is subject to a high degree of regulation, financial review and oversight by the U.S. government. All revenues are presented net of tax.
Research and Development	Research and Development Research and development costs are expensed as incurred in connection with the company’s programs for the development of products and processes. Costs incurred in connection with these programs, the majority of which are included in cost of sales, amounted to $27 million, $28 million and $26 million for the years ended December 31, 2017, 2016 and 2015, respectively.
Currency Translation	Currency Translation Assets and liabilities of foreign operations with a functional currency other than the U.S. dollar are translated using period-end exchange rates, and revenues and expenses are translated using average exchange rates during each period. Translation gains and losses are reported in accumulated other comprehensive earnings as a component of shareholders’ equity.

Critical and Significant Accounting (Policies)

12 Months Ended

Dec. 31, 2017

Critical and Significant Accounting Policies

The company records acquisitions resulting in the consolidation of an enterprise using the purchase method of accounting. Under this method, the acquiring company records the assets acquired, including intangible assets that can be identified and named, 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 assets acquired and liabilities assumed is recorded as goodwill. If the assets acquired, net of liabilities assumed, are greater than the purchase price paid, then a bargain purchase has occurred and the company will recognize the gain immediately in earnings. Among other sources of relevant information, the company uses independent appraisals and actuarial or other valuations to assist in determining the estimated fair values of the assets and liabilities. Various assumptions are used in the determination of these estimated fair values including discount rates, market and volume growth rates, product selling prices, production costs and other prospective financial information. Transaction costs associated with acquisitions are expensed as incurred and included in the business consolidation and other activities line of the consolidated statement of earnings.

For acquisitions where the company already owns an equity investment in the acquired company, the company will recognize in earnings, upon the completion of the acquisition, a gain or loss related to the company’s existing equity investment. This gain or loss is calculated based on the fair value of the equity investment as compared to the carrying value of the existing equity investment on the date of acquisition.

When the company purchases additional interests of consolidated subsidiaries that does not result in a change in control, the difference between the fair value and carrying value of the noncontrolling interests acquired is accounted for in the common stock line within shareholders' equity.

Exit and Other Closure Costs (Business Consolidation Costs)

The company estimates its liabilities for business closure activities by accumulating detailed estimates of costs and asset sale proceeds, if any, for each business consolidation initiative. This includes the estimated costs of employee severance, pension and related benefits; impairment of property and equipment and other assets, including estimates of net realizable value; accelerated depreciation; termination payments for contracts and leases; contractual obligations; and any other qualifying costs related to the exit plan. These estimated costs are grouped by specific projects within the overall exit plan and are then monitored on a monthly basis. Such charges represent management’s best estimates, but require assumptions about the plans that may change over time. Changes in estimates for individual locations and other matters are evaluated periodically to determine if a change in estimate is required for the overall restructuring plan. Subsequent changes to the original estimates are included in current earnings and identified as business consolidation gains or losses.

Defined Benefit Pension Plans and Other Employee Benefits

The company has defined benefit plans that cover a significant portion of its employees. The company also has postretirement plans that provide certain medical benefits and life insurance for retirees and eligible dependents and, to a lesser extent, participates in multi-employer defined benefit plans for which Ball is not the sponsor. For the company-sponsored plans, the relevant accounting guidance requires that management make certain assumptions relating to the long-term rate of return on plan assets, discount rates used to determine the present value of future obligations and expenses, salary inflation rates, health care cost trend rates, mortality rates and other assumptions. The company believes that the accounting estimates related to our pension and postretirement plans are critical accounting estimates because they are highly susceptible to change from period to period based on the performance of plan assets, actuarial valuations, market conditions and contracted benefit changes. The selection of assumptions is based on historical trends and known economic and market conditions at the time of valuation, as well as independent studies of trends performed by the company’s actuaries. However, actual results may differ substantially from the estimates that were based on the critical assumptions.

The company recognizes the funded status of each defined benefit pension plan and other postretirement benefit plans in the consolidated balance sheet. Each overfunded plan is recognized as an asset, and each underfunded plan is recognized as a liability. Pension plan liabilities are revalued annually, or when an event occurs that requires remeasurement, based on updated assumptions and information about the individuals covered by the plan. For pension plans, accumulated actuarial gains and losses in excess of a 10 percent corridor and the prior service cost are amortized on a straight-line basis from the date recognized over the average remaining service period of active participants or over the average life expectancy for plans with significant inactive participants. For other postemployment benefits, the 10 percent corridor is not used. The majority of costs related to defined benefit and other postretirement plans are included in cost of sales; the remainder is included in selling, general and administrative expenses.

In addition to defined benefit and postretirement plans, the company maintains reserves for employee medical claims, up to our insurance stop-loss limit, and workers’ compensation claims. These are regularly evaluated and revised, as needed, based on a variety of information, including historical experience, actuarial estimates and current employee statistics.

Income Taxes

Deferred income taxes reflect the future tax consequences of differences between the tax bases of assets and liabilities and their financial reporting amounts at each balance sheet date, based upon enacted income tax laws and tax rates. Income tax expense or benefit is provided based on earnings reported in the financial statements. The provision for income tax expense or benefit differs from the amounts of income taxes currently payable because certain items of income and expense included in the consolidated financial statements are recognized in different time periods by taxing authorities.

Deferred tax assets, including operating loss, capital loss and tax credit carryforwards, are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that any portion of these tax attributes will not be realized. In addition, from time to time, management must assess the need to accrue or disclose uncertain tax positions for proposed adjustments from various federal, state and foreign tax authorities who regularly audit the company in the normal course of business. In making these assessments, management must often analyze complex tax laws of multiple jurisdictions, including many foreign jurisdictions. The accounting guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The company records the related interest expense and penalties, if any, as tax expense in the tax provision.

Derivative Financial Instruments

The company uses derivative financial instruments for the purpose of hedging commercial risk exposures to fluctuations in interest rates, currency exchange rates, raw material costs, inflation rates and common share prices. The company’s derivative instruments are recorded in the consolidated balance sheets at fair value. The company values each derivative financial instrument either by using a single valuation technique based on observable market inputs performed internally or by obtaining valuation information from a reliable and observable market source. For a derivative designated as a cash flow hedge, the derivative's mark to fair value is initially recorded as a component of accumulated other comprehensive earnings and subsequently reclassified into earnings when the hedged item affects earnings, unless it is probable that the forecasted transaction will not occur. Derivatives that do not qualify for hedge accounting are marked to fair value with gains and losses immediately recorded in earnings. In the consolidated statements of cash flows, derivative activities are classified based on the cash flows of the items being hedged.

Realized gains and losses from hedges are classified in the consolidated statements of earnings consistent with the accounting treatment of the items being hedged. Upon the early dedesignation of an effective derivative contract, the gains or losses are deferred in accumulated other comprehensive earnings until the originally hedged item affects earnings unless it is probable the hedged item will not occur at which time it is recognized immediately. Any gains or losses incurred after the dedesignation date are recorded in earnings immediately.

Contingencies

The company is subject to various legal proceedings and claims, including those that arise in the ordinary course of business. The company records loss contingencies when it determines that the outcome of the future event is probable of occurring and the amount of the loss can be reasonably estimated. Gain contingencies are recognized in the financial statements when they are realized.

The determination of a reserve for a loss contingency is based on management’s judgment of probability and estimates with respect to the likelihood of an outcome and valuation of the future event. Liabilities are recorded or adjusted when events or circumstances cause these judgments or estimates to change. In assessing whether a loss is probable, Ball may consider the following factors, among others: the nature of the litigation, claim or assessment; available information, opinions or views of legal counsel and other advisors; and the experience gained from similar cases by the company and others. The company provides disclosures for material contingencies when there is a reasonable possibility that a loss or an additional loss may be incurred. Actual amounts realized upon settlement of contingencies may be different than amounts recorded and disclosed, and could have a significant impact on the company's consolidated financial statements.

Principles of Consolidation and Basis of Presentation

The consolidated financial statements include the accounts of Ball, its consolidated subsidiaries, and variable interest entities in which the company is considered to be the primary beneficiary. Equity investments in which the company exercises significant influence but does not control and is not the primary beneficiary are accounted for using the equity method of accounting. Investments in which the company neither exercises significant influence over the investee, nor is the primary beneficiary of the investment, are accounted for using the cost method of accounting. Intercompany transactions are eliminated in consolidation.

Inventories

Inventories are stated at the lower of cost or market using either the first-in, first-out (FIFO) cost method of accounting or the average cost method. Inventory cost is calculated for each inventory component taking into consideration the appropriate cost factors including fixed and variable overhead, material price volatility and production levels.

Impairment of Long-Lived Assets

We review long-lived assets for impairment when circumstances indicate the carrying amount of an asset or asset group may not be recoverable based on the undiscounted future cash flows of the asset. We review long-lived assets for impairment at the individual asset or the asset group level for which the lowest level of independent cash flows can be identified. If the carrying amount of the asset or asset group is determined not to be recoverable, a write-down to fair value is recorded. Fair values are determined based on quoted market values, discounted cash flows or external appraisals, as applicable.

Depreciation and Amortization

Property, plant and equipment are carried at the cost of acquisition or construction and depreciated over the estimated useful lives of the assets. Repairs and maintenance costs, including labor and material costs for major improvements such as annual production line overhauls, are expensed as incurred, unless those costs substantially increase the useful lives or capacity of the existing assets. Assets are depreciated and amortized using the straight-line method over their estimated useful lives, generally 5 to 40 years for buildings and improvements and 2 to 20 years for machinery and equipment. Finite-lived intangible assets, excluding capitalized software costs, are generally amortized over their estimated useful lives of 3 to 18 years. For capitalized software, costs are generally amortized over their estimated useful lives of 3 to 7 years. The company periodically reviews these estimated useful lives and when appropriate, changes are made prospectively.

For certain business consolidation activities, accelerated depreciation may be required over the revised remaining useful life for assets designated to be scrapped or abandoned. The accelerated depreciation related to such activities is disclosed as part of business consolidation and other activities in the appropriate period.

Environmental Reserves

The company estimates its liability for environmental matters based on, among other factors, the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of loss. The company records the best estimate of a loss when the loss is considered probable. As additional information becomes available, the company reassesses the potential liability related to pending matters and revises the estimates.

Revenue Recognition in the Packaging Segments

The company recognizes sales of products in the packaging segments when the four basic criteria of revenue recognition are met: delivery has occurred, title has transferred, there is persuasive evidence of an agreement or arrangement and the price is fixed or determinable and collection is reasonably assured. Shipping and handling costs are reported within cost of sales in the consolidated statement of earnings. All revenues are presented net of tax.

Revenue Recognition in the Aerospace Segment

Sales under long-term contracts in the aerospace segment are primarily recognized using percentage-of-completion under the cost-to-cost method of accounting. The two primary types of long-term sales contracts utilized are cost-type contracts, which are agreements to perform for cost plus an agreed upon profit component and fixed price sales contracts, which are completed for a fixed-price. Cost-type sales contracts can have different types of fee arrangements, including fixed-fee, cost, milestone and performance incentive fees, award fees or a combination thereof.

At the inception of contract performance, our estimates of base, incentive and other fees are established at a conservative estimate of profit over the period of contract performance. Throughout the period of contract performance, the company regularly reevaluates and, if necessary, revises estimates of total contract revenue, total contract cost, extent of progress toward completion, probability of receipt of any award and performance fees and any clawback provisions included in the contract. Provision for estimated contract losses, if any, is made in the period that such losses are determined to be probable. Because of sales contract payment schedules, limitations on funding and contract terms, our sales and accounts receivable generally include amounts that have been earned but not yet billed. Contract claims are only recorded if it is probable that the claim will result in additional contract revenue and the claim amounts can be reliably estimated. Revenue associated with claims is recorded only for costs already incurred and does not include a profit component. Pre-contract costs that are not approved by the customer for reimbursement are expensed as incurred. As a prime U.S. government contractor or subcontractor, the aerospace segment is subject to a high degree of regulation, financial review and oversight by the U.S. government. All revenues are presented net of tax.

Research and Development

Research and development costs are expensed as incurred in connection with the company’s programs for the development of products and processes. Costs incurred in connection with these programs, the majority of which are included in cost of sales, amounted to $27 million, $28 million and $26 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Currency Translation

Assets and liabilities of foreign operations with a functional currency other than the U.S. dollar are translated using period-end exchange rates, and revenues and expenses are translated using average exchange rates during each period. Translation gains and losses are reported in accumulated other comprehensive earnings as a component of shareholders’ equity.