Carrying Amounts of Goodwill (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Goodwill [Line Items]
Total Goodwill	$ 538.1	$ 540.7
Corporate & Institutional Services
Goodwill [Line Items]
Total Goodwill	466.6	469.2
Wealth Management
Goodwill [Line Items]
Total Goodwill	$ 71.5	$ 71.5