Investments (Mortgage Loans by Portfolio Segment) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Company-held mortgage loans held-for-investment, net
Commercial mortgage loans	$ 41,619	$ 41,088
Percentage of loans receivable on commercial mortgage loans	65.50%	68.30%
Agricultural mortgage loans	$ 12,771	$ 12,378
Percentage of loans receivable on agricultural mortgage loans	20.10%	20.60%
Residential mortgage loans	$ 8,955	$ 6,369
Percentage of loans receivable on residential mortgage loans	14.10%	10.60%
Subtotal	$ 63,345	$ 59,835
Percentage of loans receivable on subtotal	99.70%	99.50%
Valuation allowances	$ (311)	$ (305)	$ (307)	$ (322)
Percentage of loans receivable on valuation allowances	(0.50%)	(0.50%)
Subtotal mortgage loans, net	$ 63,034	$ 59,530
Percentage of loans receivable on subtotal mortgage loans held-for-investment, net	99.20%	99.00%
Percentage of residential mortgage loans - FVO	0.50%	0.50%
Percentage of loans receivable on commercial mortgage loans held by consolidated securitization entities - fair value option	0.30%	0.50%
Mortgage loans held-for-sale
Total mortgage loans, net	$ 63,553	$ 60,118
Percentage of loans held for sale on total mortgage loans, net	100.00%	100.00%
Residential — fair value option (“FVO”)
Mortgage loans held-for-sale
Total mortgage loans, net	$ 315	$ 308
Consolidated Securitization Entities
Mortgage loans held-for-sale
Total mortgage loans, net	$ 204	$ 280