BOEING 737 MAX AIRCRAFT GROUNDING	12 Months Ended
BOEING 737 MAX AIRCRAFT GROUNDING	Dec. 31, 2020
Unusual or Infrequent Items, or Both [Abstract]
Boeing 737 MAX Aircraft Grounding	BOEING 737 MAX AIRCRAFT GROUNDING AND RETURN TO SERVICE On March 13, 2019, the FAA issued an emergency order for all U.S. airlines to ground all Boeing MAX aircraft. The Company immediately complied with the order and grounded all 34 MAX aircraft in its fleet. On November 18, 2020, the FAA rescinded the emergency order and issued official requirements to enable U.S. airlines to return the Boeing 737 MAX to service. The most significant financial impacts of the grounding to the Company were the lost revenues, operating income, and operating cash flows, and delayed capital expenditures, directly associated with its grounded MAX fleet and other new aircraft that have not been able to be delivered. In July 2019, the Boeing Company announced a $4.9 billion after-tax charge for "potential concessions and other considerations to customers for disruptions related to the 737 MAX grounding." In January 2020, the Boeing Company announced an additional pre-tax charge of $2.6 billion related to "estimated potential concessions and other considerations to customers related to the 737 MAX grounding." During fourth quarter 2019, the Company entered into a Memorandum of Understanding with Boeing to compensate Southwest for estimated financial damages incurred during 2019 related to the grounding of the MAX. The terms of the agreement are confidential, but are intended to provide for a substantial portion of the Company’s financial damages associated with both the 34 MAX aircraft that were grounded as of March 13, 2019, as well as the 41 additional MAX aircraft the Company was scheduled to receive (28 owned MAX from Boeing and 13 leased MAX from third parties) from March 13, 2019 through December 31, 2019. In accordance with applicable accounting principles, the Company will account for substantially all of the proceeds received from Boeing as a reduction in cost basis spread across both the existing owned MAX in the Company’s fleet at the time, plus the Company’s future firm aircraft deliveries as of the date of the agreement. No material financial impacts of the agreement were realized in the Company’s earnings during the years ended December 31, 2019 and 2020. A total of $428 million in proceeds received in cash from Boeing are reflected within Investing Activities in the Consolidated Statement of Cash Flows for the year ended December 31, 2020. The Company is currently working to meet the FAA's official requirements to enable airlines to return the Boeing 737 MAX to service by modifying certain operating procedures, implementing enhanced Pilot training requirements, installing FAA-approved flight control software updates, and completing other required maintenance tasks specific to the MAX aircraft. The Company has scheduled the MAX return to revenue service on March 11, 2021, after the Company is expected to have met all FAA requirements and all active Pilots are expected to have received updated, MAX-related training. During December 2020, the Company took delivery of seven new leased MAX aircraft from third parties. During December 2020, the Company entered into the Boeing Agreement to compensate the Company for estimated financial damages incurred during 2020 related to the grounding of the MAX. The terms of the agreement are confidential, but the compensation will be in the form of credit memos taken against future payments due to Boeing as aircraft are delivered in accordance with the amended delivery schedule, or as future progress payments are due. In accordance with applicable accounting principles, the Company will account for substantially all of the compensation received from Boeing as a reduction in cost basis spread across both the existing owned MAX in the Company’s fleet, plus the Company’s future firm aircraft deliveries from Boeing as of the date of the agreement. No material financial impacts of the agreement were realized in the Company’s earnings during the year ended December 31, 2020.