Investments (Mortgage Loans by Portfolio Segment) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Company-held mortgage loans held-for-investment, net
Commercial mortgage loans	$ 45,165	$ 44,012
Percentage of loans receivable on commercial mortgage loans	65.10%	65.60%
Agricultural mortgage loans	$ 13,434	$ 13,188
Percentage of loans receivable on agricultural mortgage loans	19.40%	19.60%
Residential mortgage loans	$ 10,659	$ 9,734
Percentage of loans receivable on residential mortgage loans	15.40%	14.50%
Subtotal	$ 69,258	$ 66,934
Percentage of loans receivable on subtotal	99.90%	99.70%
Valuation allowances	$ (467)	$ (318)	$ (325)	$ (305)
Percentage of loans receivable on valuation allowances	(0.70%)	(0.50%)
Subtotal mortgage loans, net	$ 68,791	$ 66,616
Percentage of loans receivable on subtotal mortgage loans held-for-investment, net	99.20%	99.20%
Percentage of residential mortgage loans - FVO	0.60%	0.50%
Percentage of loans receivable on commercial mortgage loans held by consolidated securitization entities - fair value option	0.20%	0.30%
Total mortgage loans, net	$ 69,399	$ 67,102
Percentage of loans held for sale on total mortgage loans, net	100.00%	100.00%
Residential — FVO
Company-held mortgage loans held-for-investment, net
Total mortgage loans, net	$ 449	$ 314
Consolidated Securitization Entities
Company-held mortgage loans held-for-investment, net
Total mortgage loans, net	$ 159	$ 172