Commitments, Contingencies and Guarantees (Detail) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual obligation	$ 2,100
Other liabilities reserve	$ 2
Loss contingency, loss emergence period	1 year

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

No definition available.

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant