Changes in Fair Value of Level 3 Assets (Detail) (Foreign, Fair Value, Inputs, Level 3, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Foreign | Fair Value, Inputs, Level 3
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Balance at December 31 of the previous year	$ 8	$ 8
Relating to assets still held at the reporting date	1	0
Ending Balance at December 31	$ 9	$ 8