Accrued Expenses and Other Liabilities (Schedule of Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable	$ 746	$ 649
Accrued Employee Benefits	248	232
Liability for Claims and Claims Adjustment Expense	140	149	$ 169
Derivative Liability, Fair Value, Gross Liability	41	95
Deferred Revenue	32	56
Cash collateral received from counterparties	17	10
Other Accrued Liabilities	556	546
Accounts Payable and Accrued Liabilities	$ 1,780	$ 1,737