Business Segments - Summary of Operating Results by Segment (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
Revenue:
Total Revenue	$ 952	$ 1,070	$ 2,029	$ 2,142
Operating Profit:
Total Operating Profit	43	53	105	111
Operating Profit %:
Total Operating Profit %	4.50%	5.00%	5.20%	5.20%
United States (Member)
Revenue:
Total Revenue	662	742	1,366	1,454
Operating Profit:
Total Operating Profit	28	41	58	74
Operating Profit %:
Total Operating Profit %	4.20%	5.50%	4.20%	5.10%
Canada (Member)
Revenue:
Total Revenue	125	172	316	387
Operating Profit:
Total Operating Profit	2	5	18	22
Operating Profit %:
Total Operating Profit %	1.60%	2.90%	5.70%	5.70%
International [Member]
Revenue:
Total Revenue	165	156	347	301
Operating Profit:
Total Operating Profit	$ 13	$ 7	$ 29	$ 15
Operating Profit %:
Total Operating Profit %	7.90%	4.50%	8.40%	5.00%