Investments (Credit Quality of Agricultural and Residential Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	$ 12,391	$ 12,843
% of Total	100.00%	100.00%
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	2,772	958
% of Total	100.00%	100.00%
Less than 65% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	11,461	11,908
% of Total	92.50%	92.70%
65% to 75% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	729	590
% of Total	5.90%	4.60%
76% to 80% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	84	92
% of Total	0.70%	0.70%
Greater than 80% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	117	253
% of Total	0.90%	2.00%
Performing [Member]
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	2,693	929
% of Total	97.10%	97.00%
Nonperforming [Member]
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	$ 79	$ 29
% of Total	2.90%	3.00%