Investments (Mortgage Loans by Portfolio Segment) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Company-held mortgage loans held-for-investment, net
Commercial mortgage loans	$ 42,953	$ 41,088
Percentage of loans receivable on commercial mortgage loans	67.10%	68.30%
Agricultural mortgage loans	$ 12,498	$ 12,378
Percentage of loans receivable on agricultural mortgage loans	19.50%	20.60%
Residential mortgage loans	$ 8,273	$ 6,369
Percentage of loans receivable on residential mortgage loans	12.90%	10.60%
Subtotal	$ 63,724	$ 59,835
Percentage of loans receivable on subtotal	99.50%	99.50%
Valuation allowances	$ (325)	$ (305)	$ (294)	$ (322)
Percentage of loans receivable on valuation allowances	(0.50%)	(0.50%)
Subtotal mortgage loans, net	$ 63,399	$ 59,530
Percentage of loans receivable on subtotal mortgage loans held-for-investment, net	99.00%	99.00%
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	0.40%	0.50%
Mortgage loans held-for-sale
Total mortgage loans, net	$ 64,010	$ 60,118
Percentage of loans held for sale on total mortgage loans, net	100.00%	100.00%
Residential mortgage loans — FVO
Mortgage loans held-for-sale
Total mortgage loans, net	$ 345	$ 308
Consolidated Securitization Entities
Mortgage loans held-for-sale
Total mortgage loans, net	$ 266	$ 280