Components of Tax Charge (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Taxes [Line Items]
Ordinary income taxed at estimated annual effective tax rate, Income before tax	$ 39	$ 52	$ 482	$ 369
Write-off of uncollectible accounts receivable balance in North America, Income before tax			(12)
Tax adjustment relating to make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs, Income before tax
Make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs, Income before tax				(171)
Impact of reduction in UK tax rate on deferred tax balances, Income before tax
Net adjustment in respect of prior periods, Income before tax
Non-taxable gain (loss)on disposal of operations, Income before tax	(1)		(1)	4
Benefit derived from the reduction in estimate of annual effective tax rate applied to ordinary income of the prior two quarters, Income before tax
(LOSS) INCOME BEFORE INCOME TAXES AND INTEREST IN EARNINGS OF ASSOCIATES	38	52	469	202
Ordinary income taxed at estimated annual effective tax rate, Tax amount	(9)	(11)	(117)	(82)
Write-off of uncollectible accounts receivable balance in North America, Tax amount			5
Tax adjustment relating to make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs, Tax amount		(1)
Make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs, Tax amount				46
Impact of reduction in UK tax rate on deferred tax balances, Tax amount	1	2	1	2
Net adjustment in respect of prior periods, Tax amount	(3)		(3)
Non-tax deductible loss on disposal of operations, Tax amount
Benefit derived from the reduction in estimate of annual effective tax rate applied to ordinary income of the prior two quarters, Tax amount	1	8
Tax amount as reported	$ (10)	$ (2)	$ (114)	$ (34)
Estimated annual effective tax rate applicable to ordinary income	24.00%	22.00%	24.00%	22.00%
Effective tax rate on write-off of uncollectible accounts receivable balance in North America			41.00%
Tax adjustment relating to make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs, Effective tax rate
Effective income tax rate on make-whole on repurchase and redemption of senior notes and write-off of unamortized debt issuance costs				27.00%
Impact of reduction in UK tax rate on deferred tax balances, Effective tax rate
Net adjustment in respect of prior periods, Effective tax rate
Non-tax deductible gain(loss) on disposal of operations, Effective tax rate
Benefit derived from the reduction in estimate of annual effective tax rate applied to ordinary income of the prior two quarters, Effective tax rate
Effective tax rate as reported	26.00%	4.00%	24.00%	17.00%