Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets
Amortized cost of fixed maturity securities available-for-sale	$ 58,599	$ 57,289
Cost of equity securities available-for-sale	212	280
Mortgage loans valuation allowances	46	40
Mortgage loans, at estimated fair value, relating to variable interest entities	10,640	9,290
Short-term investments, principally at estimated fair value (includes $0 and $344, respectively, relating to variable interest entities)	269	1,272
Cash and cash equivalents, principally at estimated fair value(includes $0 and $3,078, respectively, relating to variable interest entities)	1,363	5,057
Accrued investment income relating to variable interest entities	575	668
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	46	1,904
Other liabilities relating to variable interest entities	$ 4,419	$ 5,445
Equity
Common stock, par value	$ 25,000	$ 25,000
Common stock, shares authorized	4,000	4,000
Common stock, shares issued	3,000	3,000
Common stock, shares outstanding	3,000	3,000
Variable interest entities
Assets
Mortgage loans, at estimated fair value, relating to variable interest entities	$ 115	$ 136
Short-term investments, principally at estimated fair value (includes $0 and $344, respectively, relating to variable interest entities)	0	344
Cash and cash equivalents, principally at estimated fair value(includes $0 and $3,078, respectively, relating to variable interest entities)	0	3,078
Accrued investment income relating to variable interest entities	1	1
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	11	23
Other liabilities relating to variable interest entities	$ 0	$ 1