Acquisitions and dispositions- Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended				0 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Apr. 23, 2014 Mexico Corporate Trust	May 31, 2013 SourceNet	Sep. 27, 2013 Newton Private Cients	May 01, 2014 HedgeMark International, LLC	May 01, 2014 HedgeMark International, LLC
Business Acquisition [Line Items]
Contingent payments	$ 0	$ 1,000,000
Potential obligation to pay additional consideration, upper limit	5,000,000	5,000,000
Business combination contingent consideration arrangement time period of measurement		3 months
Acquisitions
Ownership percentage acquired (percent)										65.00%
Payments to acquire business									26,000,000
Ownership percentage prior to acquisition										35.00%
Goodwill	17,992,000,000	17,992,000,000	18,025,000,000	18,073,000,000	18,075,000,000					47,000,000
Intangible assets										1,000,000
Dispositions
Dispositions, net of cash		64,000,000	84,000,000			65,000,000	11,000,000	120,000,000
Pretax gain on sale							2,000,000	27,000,000
After-tax gain on sale						4,000,000	10,000,000	5,000,000
Goodwill written off related to sale of business unit						8,000,000		69,000,000
Indefinite-lived intangible assets, written off related to sale of business unit						$ 1,000,000		$ 7,000,000