Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Investments in foreign subsidiaries	$ 3,400
Effective tax rate	29.10%	28.50%	30.10%
Valuation allowances	$ (69)	$ 15	$ 10
Valuation allowances, beginning balance	$ (14)	(9)	(3)
Net Operating Loss Carryforwards	80.00%
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate	$ 53	51	71
Accrued interest and penalties	8	7	10
Putnam and issues included in consolidated mmc tax returns	74	97	128	$ 117
Federal
Tax Credit Carryforward [Line Items]
Operating loss carryforwards tax benefits	10
State and Local
Tax Credit Carryforward [Line Items]
Operating loss carryforwards tax benefits	55
Non-U.S.
Tax Credit Carryforward [Line Items]
Operating loss carryforwards tax benefits	36
Putnam and Kroll
Tax Credit Carryforward [Line Items]
Putnam and issues included in consolidated mmc tax returns	1	$ 2	$ 2
Minimum
Tax Credit Carryforward [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	0
Maximum
Tax Credit Carryforward [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	$ 8