Long-Term Incentive Employee Compensation - Outstanding RSUs, Cash Settled RSUs and PSUs (Detail) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity settled RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity and Cash settled shares	0.7	1.0	1.1	[1]
Cash settled RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity and Cash settled shares	0.1	0.1	0.1
TSR Plan Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity and Cash settled shares	0.2	0.1	0
ROIC Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity and Cash settled shares	0.1	0.1	0

[1] (a)Included in the 2012 equity settled RSU's are 0.2 of Restricted Stock Awards that vested and were issued during March of 2013.