Income Taxes (Reconciliation of Income Tax Provision) (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Approved change in income tax accounting method		$ 300
Reconciliation of the income tax provision
Tax at U.S. statutory rate (as a percent)	35.00%	35.00%	35.00%
Changes in taxes resulting from:
Net income (loss) attributable to noncontrolling interests (as a percent)	(2.00%)	(5.20%)	(2.50%)
Dividend exclusion (as a percent)	(6.70%)	(4.70%)	(5.10%)
Low income housing tax credit (as a percent)	(3.00%)	(2.10%)	(2.70%)
Foreign tax credits, net of addback (as a percent)	(2.10%)	(2.00%)	(0.90%)
State taxes, net of federal benefit (as a percent)		1.60%	0.50%
Tax-exempt interest income (as a percent)		(0.70%)	(0.90%)
Taxes applicable to prior years (as a percent)		(0.20%)
Other, net (as a percent)	0.10%	(0.30%)	1.60%
Income tax provision (as a percent)	21.30%	21.40%	25.00%
Benefits Tax Planning and Completion of Audits		$ 17
Accumulated earnings of foreign subsidiaries	$ 272
Aggregate U.S. federal taxes not provided on earnings of foreign subsidiaries	$ 63