Goodwill and Other Intangible Assets - Other Intangible Assets Amortization Expense Table (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 229	$ 225
Accumulated amortization	(41)	(35)
Net carrying amount	188	190
Amortization expense	6	4
Offshore Platform Leases [Member]
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	60	60
Accumulated amortization	(36)	(33)
Net carrying amount	24	27
Amortization expense	3	2
Customer Contracts [Member]
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	169	165
Accumulated amortization	(5)	(2)
Net carrying amount	164	163
Amortization expense	$ 3	$ 2