Insurance (Obligations Under Funding Agreements - FHLB Common Stock) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank of New York
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank Stock	$ 733	$ 748
Federal Home Loan Bank of Des Moines
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank Stock	35	35
Federal Home Loan Bank of Pittsburgh
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank Stock	$ 11	$ 11