Fair Value Measurements - Financial Assets and Liabilities Measured on Recurring Basis (Detail) (Financial Assets and Liabilities Measured on Recurring Basis, USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets:
Assets	$ 54	$ 37
Liabilities:
Liabilities	36	44
Interest rate contracts
Liabilities:
Liabilities	13	22
Deferred compensation liabilities
Liabilities:
Liabilities	23	22
Investments in equity securities
Assets:
Assets	28	13
Plan assets for deferred compensation
Assets:
Assets	23	22
Investment in mutual funds
Assets:
Assets	2	2
Level 1
Assets:
Assets	54	37
Liabilities:
Liabilities	23	22
Level 1 | Deferred compensation liabilities
Liabilities:
Liabilities	23	22
Level 1 | Investments in equity securities
Assets:
Assets	28	13
Level 1 | Plan assets for deferred compensation
Assets:
Assets	23	22
Level 1 | Investment in mutual funds
Assets:
Assets	2	2
Level 2
Liabilities:
Liabilities	13	22
Level 2 | Interest rate contracts
Liabilities:
Liabilities	$ 13	$ 22