CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Common shares, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, shares authorized	1,250,000,000	1,250,000,000
Common shares, shares issued	314,623,268	309,399,529
Treasury shares	116,164,177	105,456,535
Consolidated Investment Entities
Receivables, fair value (in dollars)	$ 47	$ 77
Debt, fair value (in dollars)	4,677	4,450
Other liabilities, fair value (in dollars)	$ 603	$ 166