Income Taxes (Reconciliation of Income Tax Provision) (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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)	0.00%	(2.00%)	(5.20%)
Dividend exclusion (as a percent)	(7.60%)	(6.70%)	(4.70%)
Low income housing tax credit (as a percent)	(4.20%)	(3.00%)	(2.10%)
Taxes applicable to prior years (as a percent)	(3.10%)	0.00%	(0.20%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent	(2.50%)	0.00%	0.00%
State taxes, net of federal benefit (as a percent)	1.90%	0.00%	1.60%
Foreign tax credits, net of addback (as a percent)	(1.60%)	(2.10%)	(2.00%)
Tax-exempt interest income (as a percent)	(0.00%)	(0.00%)	(0.70%)
Other, net (as a percent)	(0.50%)	0.10%	(0.30%)
Income tax provision (as a percent)	17.40%	21.30%	21.40%
Benefits Tax Planning and Completion of Audits	$ 27
Accumulated earnings of foreign subsidiaries	321
Aggregate U.S. federal taxes not provided on earnings of foreign subsidiaries	$ 76