Changes in and Reclassification out of Accumulated Other Comprehensive Loss by Component - Summary of Reclassification of Accumulated Other Comprehensive Loss by Component (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amount reclassified from accumulated other comprehensive loss, net of tax	$ 5	$ 7	$ 9	$ 12
Interest rate contracts
Amount reclassified from accumulated other comprehensive loss, before tax	4	4	8	8
Amount reclassified from accumulated other comprehensive loss, tax	1	1	3	3
Amount reclassified from accumulated other comprehensive loss, net of tax	3	3	5	5
Actuarial loss
Amount reclassified from accumulated other comprehensive loss, before tax	3	5	6	9
Amount reclassified from accumulated other comprehensive loss, tax	1	1	2	2
Amount reclassified from accumulated other comprehensive loss, net of tax	$ 2	$ 4	$ 4	$ 7