Inventories, Net (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2016
Mar. 31, 2015
Sep. 30, 2015
Inventories, Net          
Finished goods $ 248   $ 248   $ 216
Work in process 257   257   250
Raw materials, parts and supplies 387   387   353
Less progress payments (10)   (10)   (7)
Total 882   882   812
Pre-production engineering costs 1,086   1,086   1,012
Inventories, net 1,968   $ 1,968   $ 1,824
Preproduction Engineering Costs Useful Life Maximum     15 years    
Pre-production engineering amortization expense $ 14 $ 9 $ 23 $ 21  
Capitalized pre-production engineering weighted average amortization period remaining     11 years    
Anticipated Amortization Expense for Pre-production Engineering Costs [Abstract]          
9/30/2016 [1]     $ 53    
9/30/2017 [1]     77    
9/30/2018 [1]     114    
9/30/2019 [1]     135    
9/30/2020 [1]     144    
Thereafter [1]     $ 559    
[1] On October 29, 2015, Bombardier announced the cancellation of the Learjet 85 program. Pre-production engineering costs associated with the Learjet 85 program have been excluded from anticipated amortization expense, as these costs are expected to be recovered through consideration received from Bombardier pursuant to contractual guarantees and not amortized against future hardware deliveries.