Significant Customers	12 Months Ended
Dec. 31, 2018
Significant Customers [Abstract]
Significant Customers	SIGNIFICANT CUSTOMERS DHL The Company has had long term contracts with DHL Network Operations (USA), Inc. and its affiliates ("DHL") since August 2003. Revenues from aircraft leases and related services performed for DHL were approximately 26%, 24% and 34% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2018, 2017 and 2016, respectively. Revenues excluding directly reimbursed expenses from continuing operations performed for DHL comprised approximately 30% and 37% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company’s balance sheets include accounts receivable with DHL of $13.4 million and $15.7 million as of December 31, 2018 and December 31, 2017, respectively. The Company leases Boeing 767 aircraft to DHL under both long-term and short-term lease agreements. Under a separate crew, maintenance and insurance (“CMI”) agreement, the Company operates Boeing 767 aircraft that DHL leases from the Company. Pricing for services provided through the CMI agreement is based on pre-defined fees, scaled for the number of aircraft operated and the number of flight crews provided to DHL for its U.S. network. The Company provides DHL with scheduled maintenance services for aircraft that DHL leases. The Company also provides Boeing 767 and Boeing 757 air cargo transportation services for DHL through additional ACMI agreements in which the Company provides the aircraft, crews, maintenance and insurance under a single contract. Revenues generated from the ACMI agreements are typically based on hours flown. The Company also provides ground equipment, such as power units, air starts and related maintenance services to DHL under separate agreements. Amazon The Company has been providing freighter aircraft and services for cargo handling and logistical support for Amazon.com Services, Inc. ("ASI"), successor to Amazon Fulfillment Services, Inc., a subsidiary of Amazon.com, Inc. ("Amazon") since September 2015. On March 8, 2016, the Company entered into an Air Transportation Services Agreement (the “ATSA”) with ASI, pursuant to which CAM leases 20 Boeing 767 freighter aircraft to ASI, including 12 Boeing 767-200 freighter aircraft for a term of five years and eight Boeing 767-300 freighter aircraft for a term of seven years. The ATSA also provides for the operation of those aircraft by the Company’s airline subsidiaries, and the management of ground services by the Company's subsidiary LGSTX Services Inc. ("LGSTX"). The ATSA became effective on April 1, 2016 and had an original term of five years. In conjunction with the execution of the ATSA, the Company and Amazon entered into an Investment Agreement and a Stockholders Agreement on March 8, 2016. The Investment Agreement calls for the Company to issue warrants in three tranches which will grant Amazon the right to acquire up to 19.9% of the Company’s outstanding common shares as described below. The first tranche of warrants, issued upon the execution of the Investment Agreement and all of which are now fully vested, granted Amazon the right to purchase approximately 12.81 million ATSG common shares, with the first 7.69 million common shares vesting upon issuance on March 8, 2016, and the remaining 5.12 million common shares vesting as the Company delivered additional aircraft leased under the ATSA. The second tranche of warrants, which were issued and vested on March 8, 2018, grants Amazon the right to purchase approximately 1.59 million ATSG common shares. The third tranche of warrants will be issued and vest on September 8, 2020, and will grant Amazon the right to purchase such additional number of ATSG common shares as is necessary to bring Amazon’s ownership to 19.9% of the Company’s pre-transaction outstanding common shares measured on a GAAP-diluted basis, adjusted for share issuances and repurchases by the Company following the date of the Investment Agreement and after giving effect to the warrants granted. The exercise price of the warrants is $9.73 per share, which represents the closing price of ATSG’s common shares on February 9, 2016. Each of the three tranches of warrants are exercisable in accordance with its terms through March 8, 2021. The Company’s accounting for the warrants has been determined in accordance with the financial reporting guidance for equity-based payments to non-employees and for financial instruments. The warrants issued to Amazon as of March 8, 2016, were recorded to stockholders equity, having a fair value of $4.89 per share. At that time, the fair value of the 7.69 million vested warrants issued to Amazon was recorded as a lease incentive asset and is being amortized against revenues over the duration of the aircraft leases. On May 12, 2016, the Company’s stockholders approved an amendment to the Certificate of Incorporation of the Company at the annual meeting of stockholders to increase the number of authorized common shares and to approve the warrants in full as required under the rules of the Nasdaq Global Select Market. The stockholders' approval enabled features of the warrants that required the vested warrants of the first tranche and the warrants of the second and third tranches to be classified as financial instruments as of May 12, 2016. Accordingly, the fair value of those warrants was measured and classified in liabilities on that date. Since May 12, 2016, 5.1 million additional warrants vested in conjunction with the execution of eight aircraft leases. As of December 31, 2018, the Company's liabilities reflected 14.83 million warrants having a fair value of $13.76 per share. During the years ended December 31, 2018 and 2017, the re-measurements of the warrants to fair value resulted in a non-operating gain of $7.4 million and non-operating losses of $81.8 million before the effect of income taxes, respectively. On December 22, 2018 the Company announced agreements with Amazon to 1) lease and operate ten additional Boeing 767-300 aircraft for ASI, 2) extend the term of the 12 Boeing 767-200 aircraft currently leased to ASI by two years to 2023 with an option for three more years, 3) extend the term of the eight Boeing 767-300 aircraft currently leased to ASI by three years to 2026 and 2027 with an option for three more years.and 4) extend the ATSA by five years through March 2026, with an option to extend for an additional three years. The Company plans to deliver five of the 767-300 aircraft in 2019 and the remainder in 2020. All ten of these aircraft leases will be for ten years. In conjunction with the commitment for ten additional 767 aircraft leases, extensions of twenty existing Boeing 767 aircraft leases and the ATSA described above, Amazon will be issued warrants for 14.8 million common shares which could expand its potential ownership in the Company to approximately 33.2%, including the warrants described above for the 2016 agreements. These new warrants will vest as existing leases are extended and additional aircraft leases are executed and added to the ATSA operations. These new warrants will expire if not exercised within seven years from their issuance date. They have an exercise price of $21.53 per share, based on the volume-weighted average price of the Company's shares over the 30 trading days immediately preceding execution of a non-binding term sheet by the parties on October 29, 2018. Additionally, Amazon will be able to earn incremental warrant rights, increasing its potential ownership from 33.2% up to approximately 39.9% of the Company, by leasing up to seventeen more cargo aircraft from the Company before January 2026. Incremental warrants granted for Amazon’s commitment to any such future aircraft leases will have an exercise price of the $21.53 referenced above, provided the parties reach binding agreements on future lease terms before April 2019. Beginning in April 2019, pricing of warrants related to future aircraft leases will be based on the volume-weighted average price of ATSG’s shares during the 30 trading days immediately preceding contractual commitment for each lease. The warrants potentially issuable under these new agreements with Amazon will require an increase in the number of authorized common shares of the Company. Management intends to submit a proposal calling for an appropriate increase in the number of authorized common shares for shareholder consideration at the Company’s next annual meeting of shareholders in May 2019. None of these warrants had been issued or vested as of December 31, 2018. Revenues from continuing operations performed for Amazon comprised approximately 27%, 44% and 29% of the Company's consolidated revenues from continuing operations for the years ending December 31, 2018, 2017 and 2016, respectively. Revenues excluding directly reimbursed expenses from continuing operations performed for Amazon comprised approximately 27% and 18% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company’s balance sheets include accounts receivable with Amazon of $29.2 million and $44.2 million as of December 31, 2018 and December 31, 2017, respectively. The Company's earnings in future periods will be impacted by the number of warrants granted, the re-measurements of warrant fair value, amortizations of the lease incentive asset and the related income tax effects. For income tax calculations, the value and timing of related tax deductions will differ from the guidance described above for financial reporting. DoD The Company is a provider of cargo and passenger airlift services to the DoD. The DoD awards flights to U.S. certificated airlines through annual contracts and through temporary "expansion" routes. Revenues from services performed for the DoD were approximately 15%, 7% and 12% of the Company's total revenues from continuing operations for the years ended December 31, 2018, 2017 and 2016, respectively, including revenues for Omni beginning November 9, 2018. Revenues excluding directly reimbursed expenses from continuing operations performed for the DoD comprised approximately 10% and 14% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company's balance sheets included accounts receivable with the DoD of $50.5 million and $6.7 million as of December 31, 2018 and December 31, 2017, respectively.

SIGNIFICANT CUSTOMERS

DHL

The Company has had long term contracts with DHL Network Operations (USA), Inc. and its affiliates ("DHL") since August 2003. Revenues from aircraft leases and related services performed for DHL were approximately 26%, 24% and 34% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2018, 2017 and 2016, respectively. Revenues excluding directly reimbursed expenses from continuing operations performed for DHL comprised approximately 30% and 37% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company’s balance sheets include accounts receivable with DHL of $13.4 million and $15.7 million as of December 31, 2018 and December 31, 2017, respectively.

The Company leases Boeing 767 aircraft to DHL under both long-term and short-term lease agreements. Under a separate crew, maintenance and insurance (“CMI”) agreement, the Company operates Boeing 767 aircraft that DHL leases from the Company. Pricing for services provided through the CMI agreement is based on pre-defined fees, scaled for the number of aircraft operated and the number of flight crews provided to DHL for its U.S. network. The Company provides DHL with scheduled maintenance services for aircraft that DHL leases. The Company also provides Boeing 767 and Boeing 757 air cargo transportation services for DHL through additional ACMI agreements in which the Company provides the aircraft, crews, maintenance and insurance under a single contract. Revenues generated from the ACMI agreements are typically based on hours flown. The Company also provides ground equipment, such as power units, air starts and related maintenance services to DHL under separate agreements.

Amazon

The Company has been providing freighter aircraft and services for cargo handling and logistical support for Amazon.com Services, Inc. ("ASI"), successor to Amazon Fulfillment Services, Inc., a subsidiary of Amazon.com, Inc. ("Amazon") since September 2015. On March 8, 2016, the Company entered into an Air Transportation Services Agreement (the “ATSA”) with ASI, pursuant to which CAM leases 20 Boeing 767 freighter aircraft to ASI, including 12 Boeing 767-200 freighter aircraft for a term of five years and eight Boeing 767-300 freighter aircraft for a term of seven years. The ATSA also provides for the operation of those aircraft by the Company’s airline subsidiaries, and the management of ground services by the Company's subsidiary LGSTX Services Inc. ("LGSTX"). The ATSA became effective on April 1, 2016 and had an original term of five years.

In conjunction with the execution of the ATSA, the Company and Amazon entered into an Investment Agreement and a Stockholders Agreement on March 8, 2016. The Investment Agreement calls for the Company to issue warrants in three tranches which will grant Amazon the right to acquire up to 19.9% of the Company’s outstanding common shares as described below. The first tranche of warrants, issued upon the execution of the Investment Agreement and all of which are now fully vested, granted Amazon the right to purchase approximately 12.81 million ATSG common shares, with the first 7.69 million common shares vesting upon issuance on March 8, 2016, and the remaining 5.12 million common shares vesting as the Company delivered additional aircraft leased under the ATSA. The second tranche of warrants, which were issued and vested on March 8, 2018, grants Amazon the right to purchase approximately 1.59 million ATSG common shares. The third tranche of warrants will be issued and vest on September 8, 2020, and will grant Amazon the right to purchase such additional number of ATSG common shares as is necessary to bring Amazon’s ownership to 19.9% of the Company’s pre-transaction outstanding common shares measured on a GAAP-diluted basis, adjusted for share issuances and repurchases by the Company following the date of the Investment Agreement and after giving effect to the warrants granted. The exercise price of the warrants is $9.73 per share, which represents the closing price of ATSG’s common shares on February 9, 2016. Each of the three tranches of warrants are exercisable in accordance with its terms through March 8, 2021.

The Company’s accounting for the warrants has been determined in accordance with the financial reporting guidance for equity-based payments to non-employees and for financial instruments. The warrants issued to Amazon as of March 8, 2016, were recorded to stockholders equity, having a fair value of $4.89 per share. At that time, the fair value of the 7.69 million vested warrants issued to Amazon was recorded as a lease incentive asset and is being amortized against revenues over the duration of the aircraft leases. On May 12, 2016, the Company’s stockholders approved an amendment to the Certificate of Incorporation of the Company at the annual meeting of stockholders to increase the number of authorized common shares and to approve the warrants in full as required under the rules of the Nasdaq Global Select Market. The stockholders' approval enabled features of the warrants that required the vested warrants of the first tranche and the warrants of the second and third tranches to be classified as financial instruments as of May 12, 2016. Accordingly, the fair value of those warrants was measured and classified in liabilities on that date. Since May 12, 2016, 5.1 million additional warrants vested in conjunction with the execution of eight aircraft leases. As of December 31, 2018, the Company's liabilities reflected 14.83 million warrants having a fair value of $13.76 per share. During the years ended December 31, 2018 and 2017, the re-measurements of the warrants to fair value resulted in a non-operating gain of $7.4 million and non-operating losses of $81.8 million before the effect of income taxes, respectively.

On December 22, 2018 the Company announced agreements with Amazon to 1) lease and operate ten additional Boeing 767-300 aircraft for ASI, 2) extend the term of the 12 Boeing 767-200 aircraft currently leased to ASI by two years to 2023 with an option for three more years, 3) extend the term of the eight Boeing 767-300 aircraft currently leased to ASI by three years to 2026 and 2027 with an option for three more years.and 4) extend the ATSA by five years through March 2026, with an option to extend for an additional three years. The Company plans to deliver five of the 767-300 aircraft in 2019 and the remainder in 2020. All ten of these aircraft leases will be for ten years.

In conjunction with the commitment for ten additional 767 aircraft leases, extensions of twenty existing Boeing 767 aircraft leases and the ATSA described above, Amazon will be issued warrants for 14.8 million common shares which could expand its potential ownership in the Company to approximately 33.2%, including the warrants described above for the 2016 agreements. These new warrants will vest as existing leases are extended and additional aircraft leases are executed and added to the ATSA operations. These new warrants will expire if not exercised within seven years from their issuance date. They have an exercise price of $21.53 per share, based on the volume-weighted average price of the Company's shares over the 30 trading days immediately preceding execution of a non-binding term sheet by the parties on October 29, 2018.

Additionally, Amazon will be able to earn incremental warrant rights, increasing its potential ownership from 33.2% up to approximately 39.9% of the Company, by leasing up to seventeen more cargo aircraft from the Company before January 2026. Incremental warrants granted for Amazon’s commitment to any such future aircraft leases will have an exercise price of the $21.53 referenced above, provided the parties reach binding agreements on future lease terms before April 2019. Beginning in April 2019, pricing of warrants related to future aircraft leases will be based on the volume-weighted average price of ATSG’s shares during the 30 trading days immediately preceding contractual commitment for each lease.

The warrants potentially issuable under these new agreements with Amazon will require an increase in the number of authorized common shares of the Company. Management intends to submit a proposal calling for an appropriate increase in the number of authorized common shares for shareholder consideration at the Company’s next annual meeting of shareholders in May 2019. None of these warrants had been issued or vested as of December 31, 2018.

Revenues from continuing operations performed for Amazon comprised approximately 27%, 44% and 29% of the Company's consolidated revenues from continuing operations for the years ending December 31, 2018, 2017 and 2016, respectively. Revenues excluding directly reimbursed expenses from continuing operations performed for Amazon comprised approximately 27% and 18% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company’s balance sheets include accounts receivable with Amazon of $29.2 million and $44.2 million as of December 31, 2018 and December 31, 2017, respectively.

The Company's earnings in future periods will be impacted by the number of warrants granted, the re-measurements of warrant fair value, amortizations of the lease incentive asset and the related income tax effects. For income tax calculations, the value and timing of related tax deductions will differ from the guidance described above for financial reporting.

DoD

The Company is a provider of cargo and passenger airlift services to the DoD. The DoD awards flights to U.S. certificated airlines through annual contracts and through temporary "expansion" routes. Revenues from services performed for the DoD were approximately 15%, 7% and 12% of the Company's total revenues from continuing operations for the years ended December 31, 2018, 2017 and 2016, respectively, including revenues for Omni beginning November 9, 2018. Revenues excluding directly reimbursed expenses from continuing operations performed for the DoD comprised approximately 10% and 14% of the Company's consolidated revenues from continuing operations for the years ended December 31, 2017 and 2016, respectively. The Company's balance sheets included accounts receivable with the DoD of $50.5 million and $6.7 million as of December 31, 2018 and December 31, 2017, respectively.