Restructuring Charges- by Business Segment (Detail) (Operational Efficiency Initiatives 2011, USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended		27 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring charge	$ 5	$ (2)	$ 2	$ (107)
Total charges since inception					110
Investment Management
Restructuring Cost and Reserve [Line Items]
Restructuring charge	(1)	(28)
Total charges since inception					49
Investment Services
Restructuring Cost and Reserve [Line Items]
Restructuring charge	0	(21)
Total charges since inception					60
Other
Restructuring Cost and Reserve [Line Items]
Restructuring charge	(4)	47
Total charges since inception					$ 1