XML 37 R23.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value Measurements (Additional Information) (Detail)
$ in Billions
Sep. 30, 2017
USD ($)
Fair Value Measurements [Line Items]  
Debt obligations, carrying amount $ 28.6
Level 2  
Fair Value Measurements [Line Items]  
Debt obligations, fair value $ 30.7