Investments (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	$ 367	$ 443
Investments in equity affiliates
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	221	295
Marketable equity securities - Trading (See Note 9) | Trading
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	77	74
Other
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	$ 69	$ 74