Commitments, Contingencies and Guarantees (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 27, 2018	Sep. 27, 2018	Dec. 31, 2017	Sep. 28, 2017	Dec. 31, 2016
Commitments Contingencies And Guarantees [Abstract]
Litigation settlement amount against Boeing	$ 139,000,000
Current Period Forward Loss Recorded		$ (1,700,000)
Service warranty roll forward
Product Warranty And Extraordinary Rework		166,400,000
Charges to costs and expenses	7,200,000
Product Warranty Accrual, Payments	(3,700,000)
Product Warranty And Extraordinary Rework	169,400,000	169,400,000	$ 166,400,000
Product Warranty Extraordinary Rework Accrual Currency Translation Increase Decrease	(500,000)
Commitments Contingencies And Guarantees Textuals [Abstract]
Outstanding amount of guarantees	18,800,000	18,800,000	23,200,000
Restricted Cash and Investments, Noncurrent	20,200,000	20,200,000	20,000,000	$ 20,000,000	$ 19,900,000
Product Liability Accrual, Component Amount	104,300,000	$ 104,300,000	101,000,000
Product Liability Contingency, Loss Exposure in Excess of Accrual, Best Estimate	$ 174,700,000.0		$ 223,000,000.0
Loss Contingency, Allegations		Contractual Terms Clarification. On July 6, 2018, Spirit filed a complaint in Washington Superior Court captioned Spirit AeroSystems, Inc. v. The Boeing Company (No. 18-2-16649-7  SEA).  Spirit is seeking payment of money that Boeing owes Spirit for product ordered by Boeing and delivered by Spirit. As of the date of filing the complaint, Boeing has underpaid Spirit approximately $64.0. Boeing claims to be withholding money due to customer warranty claims, which are technical in nature and largely relate to designs that predate Spirit’s separation from Boeing in 2005.  Spirit disputes its liability for those claims.  Spirit is also asking the court to clarify the parties’ contractual obligations, including that Boeing has no right under the parties’ contracts to withhold money presently due based on disputed warranty claims on past orders. On September 5, 2018, Boeing moved to dismiss three of Spirit’s claims without prejudice and one claim with prejudice. The parties are currently briefing this motion, and the Court has scheduled oral argument for November 16, 2018. Discovery in the case is ongoing.
Loss Contingency, Management's Assessment and Process		On October 1, 2018, the Company received notice of a claim related to factory disruptions. Claims are inherently uncertain as they typically include many unsubstantiated items and factual disputes. As such, the Company does not believe it is possible to develop an estimate of reasonably possible loss for this matter. The Company has requested further information and supporting documentation and will continue to re-evaluate the claim. The Company usually resolves claims received in the ordinary course of business in the context of its broad, long-term relationships.