XML 13 R45.htm IDEA: XBRL DOCUMENT v3.19.3
Goodwill and Acquired Intangible Assets - Aggregate Amortization Expense for Acquired Intangible Assets (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]          
Amortization expense $ 1 $ 1 $ 4 $ 5 $ 7
Amortization expense - Remainder of 2019 6   6    
Amortization expense - 2020 4   4    
Amortization expense - 2021 4   4    
Amortization expense - 2022 $ 2   $ 2