Long-Term Incentive Employee Compensation Rollforward of Outstanding Restricted Stock (Detail) - RSUs, PSUs and RSAs [Member] - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Beginning Outstanding, shares	1.1		1.3	1.2
Granted , shares	0.5		0.4	0.6
Performance Adjustment, shares	0.1	[1]	0.0	0.0
Lapsed, shares	(0.3)		(0.5)	(0.4)
Cancelled, shares	(0.1)		(0.1)	(0.1)
Ending Outstanding, shares	1.3		1.1	1.3
Performance Units Vested Not Yet Issued	0.3		0.0	0.0
Outstanding, Weighted Average Grant Date Fair Value	$ 31.70		$ 24.17	$ 21.06
Granted, Weighted Average Grant Date Fair Value	41.34		43.88	28.16
Performance Adjustment, Weighted Average Grant Date Fair Value	29.59		0.00	0.00
Lapsed, Weighted Average Grant Date Fair Value	24.09		21.62	20.25
Canceled, Weighted Average Grant Date Fair Value	35.89		27.33	22.68
Outstanding, Weighted Average Grant Date Fair Value	36.56		31.70	24.17
Weighted Average Grant Date Fair Value of Performance Units Vested Not Yet Issued	$ 29.59		$ 0.00	$ 0.00

[1] (a)Represents the adjustment to the number of shares to be issued above target for performance results achieved relative to PSUs granted in 2013 that vested on December 31, 2015.