Retirement Plans and Profit Sharing Arrangements (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of unrealized losses included in other comprehensive income
Net unrealized defined benefit losses at the beginning of the period	$ (75)	$ (24)	$ (20)
Net losses	(23)	(77)	(4)
Prior service credit	2	2	2
Income tax benefit	9	28	2
Net unrealized defined benefit losses at the end of the period	(91)	(75)	(24)
Percentage of matching contribution by an employer	5.00%
Minimum service period for eligibility under the defined contribution plan	60 days
Period of graded schedule for vesting match contributions	5 years
Defined contribution plan expense	36	33	32
Profit sharing plan
Threadneedle Profit Sharing Arrangements
Percentage of profit sharing	30.00%
Compensation expense (benefit) related to the employee profit sharing plan	$ 67	$ 54	$ 52