Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investments:
Amortized cost of fixed maturity securities available-for-sale	$ 47,307	$ 44,215
Cost of equity securities available-for-sale	293	295
Mortgage loans:
Valuation allowances for held-for-investment	41	61
Mortgage loans, at estimated fair value, relating to variable interest entities	9,394	9,800
Accrued investment income relating to variable interest entities	628	568
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	3,582	3,857
Other liabilities relating to variable interest entities	6,195	5,384
Stockholders' Equity
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	34,595,317	34,595,317
Common stock, shares outstanding	34,595,317	34,595,317
Variable interest entities
Mortgage loans:
Mortgage loans, at estimated fair value, relating to variable interest entities	2,879	3,138
Accrued investment income relating to variable interest entities	14	14
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	2,790	3,065
Other liabilities relating to variable interest entities	$ 14	$ 14