Schedule of Details of Dividend Payments (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Equity [Abstract]
Record Date	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 28, 2013	Mar. 28, 2013	Dec. 31, 2012
Payment Date	Oct. 31, 2014	Jul. 25, 2014	Apr. 25, 2014	Jan. 31, 2014	Oct. 25, 2013	Jul. 26, 2013	Apr. 26, 2013	Jan. 25, 2013
Amount per Share	$ 0.28	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26
Total Amount	$ 43	$ 43	$ 42	$ 42	$ 42	$ 42	$ 41	$ 42