Acquisitions and Discontinued Operations - Combined Results of Discontinued Operations (Parenthetical) (Detail) (Segment, Discontinued Operations [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Charges determined by applying a matched funds transfer pricing methodology to the liabilities assumed necessary to support the discontinued operations, after tax	$ 9	$ 13	$ 30	$ 39