XML 75 R52.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value Measurements and Investments - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Feb. 01, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2015
Fair Value Measurements and Investments [Abstract]        
Impairment losses, investments   $ 0 $ 0 $ 0
Fair value, assets, level 1 to level 2 transfers, amount   0    
Non-marketable equity investments   94 46  
Goodwill and intangible asset impairment $ 0      
Trading assets, mutual fund investments related to various employee compensation plans   $ 82 $ 71