Income Taxes Level 4 Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Period Increase (Decrease)				$ 36
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions		$ 48		$ 48
Income Tax Examination, Description				The federal audit of the years 2012 and 2013 began in March 2015 and is expected to be completed in 2016. Management believes that adequate provision has been made in the financial statements for any potential adjustments that may result from tax examinations and other tax-related matters for all open tax years.
Unrecognized Tax Benefits	$ 12			$ 12		$ 48
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	133		$ 173	516	$ 439
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount	(33)		(35)	(100)	(104)
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount	(36)		(32)	(131)	(85)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	(60)		1	(57)	4
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	3		1	(6)	(3)
Income Tax Expense (Benefit)	7		$ 108	222	$ 251
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	12			12
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 60			$ 60