Subsequent Event (Notes)	3 Months Ended
Mar. 28, 2024
Subsequent Event [Line Items]
Subsequent Events [Text Block]	26. Subsequent Events As described in the Form 8-K filed by the Company on April 23, 2024, on April 18, 2024, the Company entered into the MOA with Boeing to provide $425.0 of cash advances, based upon the Company maintaining a production rate that supports Boeing’s production demand in accordance with certain long-term supply agreements, which Spirit expects to receive in the second quarter of 2024. The MOA requires repayment installments of $36.6 on June 12, 2024, $89.5 on July 17, 2024, $150.6 on August 14, 2024, $134.3 on September 18, 2024, and $14.0 on October 16, 2024. The Company’s repayment obligation will be accelerated, and any outstanding amount advanced under the agreement will immediately become due and payable, in the event that (i) the Company fails to make any repayment in full on the applicable Repayment Date, (ii) the Company fails to submit a satisfactory written confirmation that the Company is able to and intends to make the required repayment thirty days prior to each Repayment Date, as required under the agreement, (iii) the Company repudiates any performance obligation under this MOA or certain of the Company’s existing agreements with Boeing, (iv) there occurs, either as to Spirit, Spirit Holdings or any of their respective subsidiaries, any of the events of default (generally relating to insolvency, reorganization, liquidation or similar proceedings, or to business suspension, dissolution or winding-up) described in specified provisions of the Company’s existing agreements with Boeing, then all amounts of the advances from the MOA that remain outstanding to Boeing pursuant to the repayment provisions of the MOA as of such time will become immediately due and payable. Subsequent to the end of the first quarter, Spirit received indications that Boeing expects a slower increase in production and deliveries of B787 planes. While the Company has not received a formal schedule change from its customer, based on expected changes to production and delivery schedules, the Company has completed a preliminary assessment relevant to the expected impact of this schedule change. As a result of this preliminary assessment, the Company expects to incur an incremental forward loss of approximately $50 to $60 in the second quarter of 2024 due to the impact of reduced production volumes and the ability for the Company to reduce variable costs in a timely manner and the corresponding amount of fixed overhead absorption applied to lower deliveries. This preliminary assessment is subject to change if Boeing further revises its production and delivery plans.

As described in the Form 8-K filed by the Company on April 23, 2024, on April 18, 2024, the Company entered into the MOA with Boeing to provide $425.0 of cash advances, based upon the Company maintaining a production rate that supports Boeing’s production demand in accordance with certain long-term supply agreements, which Spirit expects to receive in the second quarter of 2024.

The MOA requires repayment installments of $36.6 on June 12, 2024, $89.5 on July 17, 2024, $150.6 on August 14, 2024, $134.3 on September 18, 2024, and $14.0 on October 16, 2024. The Company’s repayment obligation will be accelerated, and any outstanding amount advanced under the agreement will immediately become due and payable, in the event that (i) the Company fails to make any repayment in full on the applicable Repayment Date, (ii) the Company fails to submit a satisfactory written confirmation that the Company is able to and intends to make the required repayment thirty days prior to each Repayment Date, as required under the agreement, (iii) the Company repudiates any performance obligation under this MOA or certain of the Company’s existing agreements with Boeing, (iv) there occurs, either as to Spirit, Spirit Holdings or any of their respective subsidiaries, any of the events of default (generally relating to insolvency, reorganization, liquidation or similar proceedings, or to business suspension, dissolution or winding-up) described in specified provisions of the Company’s existing agreements with Boeing, then all amounts of the advances from the MOA that remain outstanding to Boeing pursuant to the repayment provisions of the MOA as of such time will become immediately due and payable.

Subsequent to the end of the first quarter, Spirit received indications that Boeing expects a slower increase in production and deliveries of B787 planes. While the Company has not received a formal schedule change from its customer, based on expected changes to production and delivery schedules, the Company has completed a preliminary assessment relevant to the expected impact of this schedule change. As a result of this preliminary assessment, the Company expects to incur an incremental forward loss of approximately $50 to $60 in the second quarter of 2024 due to the impact of reduced production volumes and the ability for the Company to reduce variable costs in a timely manner and the corresponding amount of fixed overhead absorption applied to lower deliveries. This preliminary assessment is subject to change if Boeing further revises its production and delivery plans.