Long-Term Incentive Employee Compensation - Rollforward of Outstanding Stock Options (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Shares
Beginning Balance, Shares	2.7	4.3	8.0
Stock Options Granted, Shares	0.2	0.4	0.4
Stock Options Exercised, Shares	(0.8)	(1.9)	(3.8)
Stock Options Canceled or Expired, Shares	(0.2)	(0.1)	(0.3)
Stock Options Outstanding at the end of Year, Shares	1.9	2.7	4.3
Stock Options Exercisable at the end of year, Shares	1.1	1.5	2.9
Weighted Average Exercise Price
Beginning Balance, Weighted Average Exercise Price	$ 20.46	$ 18.46	$ 16.70
Stock Options Granted, Weighted Average Exercise Price	$ 43.52	$ 26.82	$ 22.80
Stock Options Exercised, Weighted Average Exercise Price	$ 17.67	$ 17.37	$ 15.35
Stock Options Canceled or Expired, Weighted Average Exercise Price	$ 24.46	$ 16.15	$ 17.21
Outstanding, Weighted Average Exercise Price	$ 24.20	$ 20.46	$ 18.46
Stock Options Exercisable at the end of year, Weighted Average Exercise Price	$ 20.26	$ 18.34	$ 17.10