Special Charges	6 Months Ended
Jun. 30, 2018
Special Charges and Credits [Abstract]
Special Charges	Special Charges Special Charges, Operating During the first quarter of 2018, the Company negotiated and amended the collective bargaining agreement with the Air Line Pilots Association, International ("ALPA"), under the guidance of the National Mediation Board ("NMB"). In connection with the amended agreement, the Company incurred a one-time ratification incentive bonus of $80.7 million, including payroll taxes, and an $8.5 million adjustment related to other contractual provisions. As a result, the Company recorded $89.3 million in special charges within operating expenses in the statement of operations for the six months ended June 30, 2018. During the second quarter of 2018, the Company paid $75.8 million of the ratification incentive bonus with the remainder expected to be paid during the third quarter of 2018. During the six months ended June 30, 2017, the Company purchased one engine which was previously financed under an operating lease agreement. The purchase price of the engine was $8.1 million, comprised of a cash payment of $3.8 million and the non-cash application of maintenance reserves and security deposits held by the previous lessor of $4.3 million. The Company estimated the fair value of the engine to be $3.1 million and recorded the purchased engine at fair value within flight equipment on the condensed balance sheets. The Company determined the valuation of the engine based on a third-party appraisal considering the condition of the engine (a Level 3 measurement). The Company recognized $4.8 million as a cost of terminating the lease within special charges on the condensed statement of operations, comprised of the excess of the purchase price paid over the fair value of the engine, less other non-cash items of $0.2 million. Special Charges, Non-Operating During the three and six months ended June 30, 2018, the Company recorded $79.4 million and $88.6 million, respectively, in special charges, non-operating within other (income) expense in the statement of operations. During the first quarter of 2018, the Company entered into an aircraft purchase agreement for the purchase of 14 A319 aircraft previously operated under operating leases by the Company. The aggregate gross purchase price for the 14 aircraft was $285.0 million, and the price for each aircraft at the time of the sale was comprised of a cash payment net of the amount of maintenance reserves and security deposits for such aircraft held by the applicable lessor pursuant to the lease for such aircraft. The contract was deemed a lease modification which resulted in a change of classification from operating leases to capital leases for the 14 aircraft. During the first quarter of 2018, the capital lease assets were recorded at the fair value of the aircraft within flight equipment on the condensed balance sheets. During the second quarter of 2018, the purchase of the 14 aircraft was completed and the obligation was accreted up to the net cash payment price with interest charges recognized in special charges, non-operating in the statement of operations. The Company determined the valuation of the aircraft based on third-party appraisals considering the condition of the aircraft (a Level 3 measurement).

Special Charges

Special Charges, Operating

During the first quarter of 2018, the Company negotiated and amended the collective bargaining agreement with the Air Line Pilots Association, International ("ALPA"), under the guidance of the National Mediation Board ("NMB"). In connection with the amended agreement, the Company incurred a one-time ratification incentive bonus of $80.7 million, including payroll taxes, and an $8.5 million adjustment related to other contractual provisions. As a result, the Company recorded $89.3 million in special charges within operating expenses in the statement of operations for the six months ended June 30, 2018. During the second quarter of 2018, the Company paid $75.8 million of the ratification incentive bonus with the remainder expected to be paid during the third quarter of 2018.

During the six months ended June 30, 2017, the Company purchased one engine which was previously financed under an operating lease agreement. The purchase price of the engine was $8.1 million, comprised of a cash payment of $3.8 million and the non-cash application of maintenance reserves and security deposits held by the previous lessor of $4.3 million. The Company estimated the fair value of the engine to be $3.1 million and recorded the purchased engine at fair value within flight equipment on the condensed balance sheets. The Company determined the valuation of the engine based on a third-party appraisal considering the condition of the engine (a Level 3 measurement). The Company recognized $4.8 million as a cost of terminating the lease within special charges on the condensed statement of operations, comprised of the excess of the purchase price paid over the fair value of the engine, less other non-cash items of $0.2 million.

Special Charges, Non-Operating

During the three and six months ended June 30, 2018, the Company recorded $79.4 million and $88.6 million, respectively, in special charges, non-operating within other (income) expense in the statement of operations. During the first quarter of 2018, the Company entered into an aircraft purchase agreement for the purchase of 14 A319 aircraft previously operated under operating leases by the Company. The aggregate gross purchase price for the 14 aircraft was $285.0 million, and the price for each aircraft at the time of the sale was comprised of a cash payment net of the amount of maintenance reserves and security deposits for such aircraft held by the applicable lessor pursuant to the lease for such aircraft. The contract was deemed a lease modification which resulted in a change of classification from operating leases to capital leases for the 14 aircraft. During the first quarter of 2018, the capital lease assets were recorded at the fair value of the aircraft within flight equipment on the condensed balance sheets. During the second quarter of 2018, the purchase of the 14 aircraft was completed and the obligation was accreted up to the net cash payment price with interest charges recognized in special charges, non-operating in the statement of operations. The Company determined the valuation of the aircraft based on third-party appraisals considering the condition of the aircraft (a Level 3 measurement).