Long-Term Incentive Employee Compensation - Share-based Compensation Summary of Stock Options (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Oct. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding Number	4.3	8.0	8.0	3.7	4.0
Options Outstanding Weighted-Average Remaining Contractual Life (In Years)	4 years 2 months 12 days
Options Outstanding Weighted-Average Exercise Price	$ 18.46	$ 16.70	$ 16.70	$ 85.08	$ 80.58
Options Outstanding Aggregate Intrinsic Value	$ 21.8
Options Exercisable Number	2.9	6.3		3.0
Options Exercisable Weighted-Average Remaining Contractual Life (In Years)	2 years 7 months 6 days
Options Exercisable Weighted-Average Exercise Price	$ 17.10	$ 16.03		$ 83.72
Options Exercisable Aggregate Intrinsic Value	18.8
$10 - $15 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Minimum exercise price	$ 10
Maximum exercise price	$ 15
Options Outstanding Number	1.4
Options Outstanding Weighted-Average Remaining Contractual Life (In Years)	1 year 7 months 6 days
Options Outstanding Weighted-Average Exercise Price	$ 13.30
Options Outstanding Aggregate Intrinsic Value	14.5
Options Exercisable Number	1.4
Options Exercisable Weighted-Average Remaining Contractual Life (In Years)	1 year 7 months 6 days
Options Exercisable Weighted-Average Exercise Price	$ 13.30
Options Exercisable Aggregate Intrinsic Value	14.5
$15 - $20 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Minimum exercise price	$ 15
Maximum exercise price	$ 20
Options Outstanding Number	0.9
Options Outstanding Weighted-Average Remaining Contractual Life (In Years)	3 years 9 months 18 days
Options Outstanding Weighted-Average Exercise Price	$ 19.85
Options Outstanding Aggregate Intrinsic Value	3.4
Options Exercisable Number	0.7
Options Exercisable Weighted-Average Remaining Contractual Life (In Years)	2 years 9 months 18 days
Options Exercisable Weighted-Average Exercise Price	$ 19.82
Options Exercisable Aggregate Intrinsic Value	2.7
$20 - $26 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Minimum exercise price	$ 20
Maximum exercise price	$ 26
Options Outstanding Number	2.0
Options Outstanding Weighted-Average Remaining Contractual Life (In Years)	6 years 3 months 18 days
Options Outstanding Weighted-Average Exercise Price	$ 21.52
Options Outstanding Aggregate Intrinsic Value	3.9
Options Exercisable Number	0.8
Options Exercisable Weighted-Average Remaining Contractual Life (In Years)	4 years 1 month 6 days
Options Exercisable Weighted-Average Exercise Price	$ 21.51
Options Exercisable Aggregate Intrinsic Value	$ 1.6