CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
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	322,822,746	320,990,255
Treasury shares	151,789,486	137,880,746
Consolidated investment entities [Member]
Receivables, fair value (in dollars)	$ 70	$ 49
Other assets, fair value (in dollars)	2,065	1,936
Debt, fair value (in dollars)	6,630	6,030
Other liabilities, fair value (in dollars)	$ 221	$ 193