Accounting and Reporting Developments (Additional Information) (Detail) - USD ($) $ in Millions	Jan. 01, 2019		Jan. 01, 2018
Accounting Policies [Abstract]
Right of use asset and lease liabilities	$ 509
Impact of cumulative effect of change in accounting principles	$ 10	[1]	$ 4

[1] Related to the adoption of ASU 2016-02 as of January 1, 2019. Refer to Note 4 for additional information.