Accrued Expenses and Other Liabilities (Schedule of Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities [Abstract]
Accounts payable	$ 846	$ 746
Employee compensation and benefits	236	248
Reserves for insurance losses and loss adjustment expenses	139	140	$ 173	$ 149
Fair value of derivative contracts in a payable position	70	41
Cash collateral received from counterparties	50	17
Deferred revenue	27	32
Other liabilities	657	556
Total accrued expenses and other liabilities	$ 2,025	$ 1,780