Business Description and Basis of Presentation (Policies)
 6 Months Ended
Mar. 31, 2016
Accounting Policies [Abstract]  
Preproduction Engineering Costs Policy
The Company defers certain pre-production engineering costs during the development phase of a program in connection with long-term supply arrangements that contain contractual guarantees for reimbursement from customers. Such customer guarantees generally take the form of a minimum order quantity with quantified reimbursement amounts if the minimum order quantity is not taken by the customer. These costs are deferred to the extent of the contractual guarantees and are amortized over their estimated useful lives using a units-of-delivery method, up to 15 years. This amortization expense is included as a component of cost of sales. Amortization is based on the Company's expectation of delivery rates on a program-by-program basis and begins when the Company starts recognizing revenue as the Company delivers equipment for the program. The estimated useful life is limited to the amount of time the Company is virtually assured to earn revenues under long-term supply arrangements with the Company's customers. Pre-production engineering costs incurred pursuant to supply arrangements that do not contain contractual guarantees for reimbursement are expensed as incurred.
Customer Incentives, Policy
Rockwell Collins provides up-front sales incentives prior to delivering products or performing services to certain commercial customers in connection with sales contracts. Up-front sales incentives are recorded as a customer relationship intangible asset and are amortized using a units-of-delivery method over the period the Company has received a contractually enforceable right related to the incentives, up to 15 years after entry into service. Amortization is based on the Company's expectation of delivery rates on a program-by-program basis. Amortization begins when the Company starts recognizing revenue as the Company delivers equipment for the program.