Insurance (Guarantees Related to Annuity Contracts) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Variable Annuity Guarantees | Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 180,216	$ 181,413
Separate account value	150,726	151,901
Net amount at risk	$ 10,475	$ 10,339
Average attained age of contractholders	67 years	66 years
Variable Annuity Guarantees | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 90,785	$ 91,240
Separate account value	87,235	87,841
Net amount at risk	$ 3,412	$ 2,762
Average attained age of contractholders	66 years	66 years
Other Annuity Guarantees | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 1,583	$ 1,560
Net amount at risk	$ 425	$ 422
Average attained age of contractholders	51 years	51 years