Summary of Financial Statement Preparation and Significant Accounting Policies	3 Months Ended
Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Financial Statement Preparation and Significant Accounting Policies	SUMMARY OF FINANCIAL STATEMENT PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES Nature of Operations Air Transport Services Group, Inc. is a holding company whose principal subsidiaries include an aircraft leasing company and two U.S. certificated airlines. The Company provides airline operations, aircraft leases, aircraft maintenance and other support services primarily to the cargo transportation and package delivery industries. Through the Company's subsidiaries, it offers a range of complementary services to delivery companies, freight forwarders, airlines and government customers. The Company's leasing subsidiary, Cargo Aircraft Management, Inc. (“CAM”), leases aircraft to each of the Company's airlines as well as to non-affiliated airlines and other lessees. The airlines, ABX Air, Inc. (“ABX”) and Air Transport International, Inc. (“ATI”), each have the authority, through their separate U.S. Department of Transportation ("DOT") and Federal Aviation Administration ("FAA") certificates, to transport cargo worldwide. ATI provides passenger transportation, primarily to the U.S. Military, using "combi" aircraft, which are certified to carry passengers as well as cargo on the main deck. The Company serves a base of concentrated customers who typically have a diverse line of international cargo traffic. The Company provides aircraft and airline operations to its customers, typically under contracts providing for a combination of aircraft, crews, maintenance and insurance ("ACMI") services. In addition to its airline operations and aircraft leasing services, the Company sells aircraft parts, provides aircraft maintenance and modification services, equipment maintenance services, and operates mail and package sorting facilities. Basis of Presentation The accompanying unaudited condensed interim consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America and such principles are applied on a basis consistent with the financial statements reflected in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016 filed with the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to the rules and regulations promulgated by the SEC related to interim financial statements. In the opinion of management, the accompanying financial statements contain all adjustments, including normal recurring adjustments, necessary for the fair presentation of the Company’s results of operations and financial position for the periods presented. Due to seasonal fluctuations, among other factors common to the airline industry, the results of operations for the periods presented are not necessarily indicative of the results of operations to be expected for the entire year or any interim period. The preparation of consolidated financial statements requires management to make estimates and assumptions that affect amounts reported in the consolidated financial statements. The accounting estimates reflect the best judgment of management, but actual results could differ materially from those estimates. The accompanying condensed consolidated financial statements include the accounts of Air Transport Services Group, Inc. and its wholly-owned subsidiaries. Investments in an affiliate in which the Company has significant influence but does not exercise control are accounted for using the equity method of accounting. Using the equity method, the Company’s share of the nonconsolidated affiliate's income or loss is recognized in the consolidated statement of earnings and cumulative post-acquisition changes in the investment are adjusted against the carrying amount of the investment. Inter-company balances and transactions are eliminated. 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)” (“ASU 2014-09”). In April 2016, the FASB issued ASU No. 2016-10, "Revenue from Contracts with Customers, Identifying Performance Obligations and Licensing" clarify the accounting under ASU 2014-09 for licenses of intellectual property and for identifying distinct performance obligations in a contract. ASU 2014-09 is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. ASU 2014-09 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. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017 with earlier adoption permitted for reporting periods beginning after December 15, 2016. ASU 2014-09 may be applied using either a full retrospective approach, under which all years included in the financial statements will be presented under the revised guidance, or a modified retrospective approach, under which financial statements will be prepared under the revised guidance for the year of adoption, but not for prior years. Under the latter method, entities would recognize a cumulative catch-up adjustment to the opening balance of retained earnings at the effective date for contracts that still require performance by the entity, and disclose all line items in the year of adoption as if they were prepared under the old revenue guidance. The Company is currently evaluating the methods of adoption allowed by the new standard and the effect the standard is expected to have on the Company's consolidated financial position, results of operations or cash flows and related disclosures. The evaluation includes each of the five steps identified in the ASU 2014-09 revenue recognition model, which are as follows: 1) identify the contract with the customer; 2) identify the performance obligations in the contract; 3) determine the transaction price; 4) allocate the transaction price to the performance obligations; and 5) recognize revenue when (or as) performance obligations are satisfied. The Company's lease contracts within the scope of ASC 840, Leases, are specifically excluded from ASU 2014-09. 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 revenue and expense recognized. Additionally, industry activities and other guidance provided by regulators, standards setters, and the accounting profession may affect the Company’s assessment and implementation plans. In July 2015, FASB issued ASU "Inventory (Topic 330): Simplifying the Measurement of Inventory" ("ASU 2015-11"). ASU 2015-11 more closely aligns the measurement of inventory in GAAP with the measurement of inventory in International Financial Reporting Standards ("IFRS"). The amendment in ASU 2015-11 is for fiscal years beginning after December 15, 2016, and interim periods within fiscal years beginning after December 15, 2017. The amendment should be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. The Company does not expect the impact of adopting ASU 2015-11 to be material to the Company's financial statements and related disclosures. In March 2017, the FASB issued ASU "Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost" (ASU 2017-07"). ASU 2017-07 requires an employer to report the service cost component of retiree benefits in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost would be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. The standard is effective for annual periods beginning after December 15, 2017 and should be applied retrospectively. The Company anticipates the standard will impact the Operating Income subtotal as reported in the Company's Consolidated Statement of Operations by excluding interest expense, investment returns and other non service cost components of retiree benefit expenses. Information about interest expense, investment returns and other components of retiree benefit expenses can be found in Note H. In February 2016, the FASB issued ASU "Leases (Topic 842)" ("ASU 2016-02"), which will require the recognition of right to-use-assets and lease liabilities for leases previously classified as operating leases by lessees. The standard will take effect for annual reporting periods beginning after December 15, 2018, including interim reporting periods. Early application will be permitted for all entities. In addition, the FASB has decided to require a lessee to apply a modified retrospective transition approach for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements (the date of initial application). The modified retrospective approach would not require any transition accounting for leases that expired before the date of initial application. The FASB decided to not permit a full retrospective transition approach. The Company is currently evaluating the impact of the standard on its financial statements and disclosures. In August 2016, the FASB issued ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments" ("ASU 2016-15"). ASU 2016-15 clarifies how cash receipts and cash payments in certain transactions are presented and classified in the statement of cash flows. The effective date of this update is for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The update requires retrospective application to all periods presented but may be applied prospectively if retrospective application is impracticable. The Company is currently evaluating the impact of the adoption of the standard on the its financial statements and disclosures. In November 2016, the FASB issued ASU "Statement of Cash Flows (Topic 230): Restricted Cash" ("ASU 2016-18"). ASU 2016-18 requires that the statement of cash flows explain the changes in the combined total of restricted and unrestricted cash balance. Amounts generally described as restricted cash or restricted cash equivalents will be combined with unrestricted cash and cash equivalents when reconciling the beginning and end of period balances on the statement of cash flows. Further, the ASU requires a reconciliation of balances from the statement of cash flows to the balance sheet in situations in which the balance sheet includes more than one line item of cash, cash equivalents, and restricted cash. Companies will also be disclosing the nature of the restrictions. ASU 2016-18 is effective for financial statements issued for fiscal years beginning after December 15, 2017. The Company is currently evaluating the impact of the standard on its financial statements and disclosures. In January 2017, the FASB issued ASU "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" ("ASU 2017-04"). ASU 2017-04 will simplify the subsequent measurement of goodwill by eliminating the second step from the goodwill impairment test. ASU 2017-04 would require applying a one-step quantitative test and recording the amount of goodwill impairment as the excess of the reporting unit's carrying value over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. ASU 2017-04 does not amend the optional qualitative assessment of goodwill impairment. The amendments in ASU 2017-04 are effective for annual or any interim goodwill impairment tests for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently evaluating the impact of the standard on its financial statements and disclosures.

SUMMARY OF FINANCIAL STATEMENT PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES

Nature of Operations

Air Transport Services Group, Inc. is a holding company whose principal subsidiaries include an aircraft leasing company and two U.S. certificated airlines. The Company provides airline operations, aircraft leases, aircraft maintenance and other support services primarily to the cargo transportation and package delivery industries. Through the Company's subsidiaries, it offers a range of complementary services to delivery companies, freight forwarders, airlines and government customers.

The Company's leasing subsidiary, Cargo Aircraft Management, Inc. (“CAM”), leases aircraft to each of the Company's airlines as well as to non-affiliated airlines and other lessees. The airlines, ABX Air, Inc. (“ABX”) and Air Transport International, Inc. (“ATI”), each have the authority, through their separate U.S. Department of Transportation ("DOT") and Federal Aviation Administration ("FAA") certificates, to transport cargo worldwide. ATI provides passenger transportation, primarily to the U.S. Military, using "combi" aircraft, which are certified to carry passengers as well as cargo on the main deck.

The Company serves a base of concentrated customers who typically have a diverse line of international cargo traffic. The Company provides aircraft and airline operations to its customers, typically under contracts providing for a combination of aircraft, crews, maintenance and insurance ("ACMI") services. In addition to its airline operations and aircraft leasing services, the Company sells aircraft parts, provides aircraft maintenance and modification services, equipment maintenance services, and operates mail and package sorting facilities.

Basis of Presentation

The accompanying unaudited condensed interim consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America and such principles are applied on a basis consistent with the financial statements reflected in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016 filed with the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to the rules and regulations promulgated by the SEC related to interim financial statements. In the opinion of management, the accompanying financial statements contain all adjustments, including normal recurring adjustments, necessary for the fair presentation of the Company’s results of operations and financial position for the periods presented. Due to seasonal fluctuations, among other factors common to the airline industry, the results of operations for the periods presented are not necessarily indicative of the results of operations to be expected for the entire year or any interim period. The preparation of consolidated financial statements requires management to make estimates and assumptions that affect amounts reported in the consolidated financial statements. The accounting estimates reflect the best judgment of management, but actual results could differ materially from those estimates.

The accompanying condensed consolidated financial statements include the accounts of Air Transport Services Group, Inc. and its wholly-owned subsidiaries. Investments in an affiliate in which the Company has significant influence but does not exercise control are accounted for using the equity method of accounting. Using the equity method, the Company’s share of the nonconsolidated affiliate's income or loss is recognized in the consolidated statement of earnings and cumulative post-acquisition changes in the investment are adjusted against the carrying amount of the investment. Inter-company balances and transactions are eliminated.

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)” (“ASU 2014-09”). In April 2016, the FASB issued ASU No. 2016-10, "Revenue from Contracts with Customers, Identifying Performance Obligations and Licensing" clarify the accounting under ASU 2014-09 for licenses of intellectual property and for identifying distinct performance obligations in a contract.

ASU 2014-09 is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. ASU 2014-09 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. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017 with earlier adoption permitted for reporting periods beginning after December 15, 2016. ASU 2014-09 may be applied using either a full retrospective approach, under which all years included in the financial statements will be presented under the revised guidance, or a modified retrospective approach, under which financial statements will be prepared under the revised guidance for the year of adoption, but not for prior years. Under the latter method, entities would recognize a cumulative catch-up adjustment to the opening balance of retained earnings at the effective date for contracts that still require performance by the entity, and disclose all line items in the year of adoption as if they were prepared under the old revenue guidance.

The Company is currently evaluating the methods of adoption allowed by the new standard and the effect the standard is expected to have on the Company's consolidated financial position, results of operations or cash flows and related disclosures. The evaluation includes each of the five steps identified in the ASU 2014-09 revenue recognition model, which are as follows: 1) identify the contract with the customer; 2) identify the performance obligations in the contract; 3) determine the transaction price; 4) allocate the transaction price to the performance obligations; and 5) recognize revenue when (or as) performance obligations are satisfied. The Company's lease contracts within the scope of ASC 840, Leases, are specifically excluded from ASU 2014-09. 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 revenue and expense recognized. Additionally, industry activities and other guidance provided by regulators, standards setters, and the accounting profession may affect the Company’s assessment and implementation plans.

In July 2015, FASB issued ASU "Inventory (Topic 330): Simplifying the Measurement of Inventory" ("ASU 2015-11"). ASU 2015-11 more closely aligns the measurement of inventory in GAAP with the measurement of inventory in International Financial Reporting Standards ("IFRS"). The amendment in ASU 2015-11 is for fiscal years beginning after December 15, 2016, and interim periods within fiscal years beginning after December 15, 2017. The amendment should be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. The Company does not expect the impact of adopting ASU 2015-11 to be material to the Company's financial statements and related disclosures.

In March 2017, the FASB issued ASU "Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost" (ASU 2017-07"). ASU 2017-07 requires an employer to report the service cost component of retiree benefits in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost would be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. The standard is effective for annual periods beginning after December 15, 2017 and should be applied retrospectively. The Company anticipates the standard will impact the Operating Income subtotal as reported in the Company's Consolidated Statement of Operations by excluding interest expense, investment returns and other non service cost components of retiree benefit expenses. Information about interest expense, investment returns and other components of retiree benefit expenses can be found in Note H.

In February 2016, the FASB issued ASU "Leases (Topic 842)" ("ASU 2016-02"), which will require the recognition of right to-use-assets and lease liabilities for leases previously classified as operating leases by lessees. The standard will take effect for annual reporting periods beginning after December 15, 2018, including interim reporting periods. Early application will be permitted for all entities. In addition, the FASB has decided to require a lessee to apply a modified retrospective transition approach for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements (the date of initial application). The modified retrospective approach would not require any transition accounting for leases that expired before the date of initial application. The FASB decided to not permit a full retrospective transition approach. The Company is currently evaluating the impact of the standard on its financial statements and disclosures.

In August 2016, the FASB issued ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments" ("ASU 2016-15"). ASU 2016-15 clarifies how cash receipts and cash payments in certain transactions are presented and classified in the statement of cash flows. The effective date of this update is for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The update requires retrospective application to all periods presented but may be applied prospectively if retrospective application is impracticable. The Company is currently evaluating the impact of the adoption of the standard on the its financial statements and disclosures.

In November 2016, the FASB issued ASU "Statement of Cash Flows (Topic 230): Restricted Cash" ("ASU 2016-18"). ASU 2016-18 requires that the statement of cash flows explain the changes in the combined total of restricted and unrestricted cash balance. Amounts generally described as restricted cash or restricted cash equivalents will be combined with unrestricted cash and cash equivalents when reconciling the beginning and end of period balances on the statement of cash flows. Further, the ASU requires a reconciliation of balances from the statement of cash flows to the balance sheet in situations in which the balance sheet includes more than one line item of cash, cash equivalents, and restricted cash. Companies will also be disclosing the nature of the restrictions. ASU 2016-18 is effective for financial statements issued for fiscal years beginning after December 15, 2017. The Company is currently evaluating the impact of the standard on its financial statements and disclosures.

In January 2017, the FASB issued ASU "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" ("ASU 2017-04"). ASU 2017-04 will simplify the subsequent measurement of goodwill by eliminating the second step from the goodwill impairment test. ASU 2017-04 would require applying a one-step quantitative test and recording the amount of goodwill impairment as the excess of the reporting unit's carrying value over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. ASU 2017-04 does not amend the optional qualitative assessment of goodwill impairment. The amendments in ASU 2017-04 are effective for annual or any interim goodwill impairment tests for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently evaluating the impact of the standard on its financial statements and disclosures.