Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Deferred tax assets, tax credit carryforwards	$ 1,796
Deferred tax assets, valuation allowance	(1,057)
Deferred tax assets, net	317	$ 461
Other assets	6,153	5,663
Accrued expenses and other liabilities	1,676	1,780
Deferred tax asset
Tax Credit Carryforward [Line Items]
Deferred tax assets, tax credit carryforwards	1,796	2,002
Deferred tax assets, adjustment to loan value	366	450
Deferred tax assets, state and local taxes	168	200
Deferred tax assets, unearned insurance premiums	90	85
Deferred tax assets, hedging transactions	27	49
Deferred tax assets, tax loss carryforward	8	302
Deferred tax assets, other	222	108
Deferred tax assets, gross	2,677	3,196
Deferred tax assets, valuation allowance	(1,057)	(1,123)
Deferred tax assets, net of valuation allowance	1,620	2,073
Other assets	317	461
Deferred tax liability
Tax Credit Carryforward [Line Items]
Deferred tax liabilities, lease transactions	850	1,212
Deferred tax liabilities, deferred acquisition cost	321	269
Deferred tax liabilities, debt transactions	93	95
Deferred tax liabilities, other	56	44
Deferred tax liabilities, gross	1,320	1,620
Deferred tax assets, net	300	453
Accrued expenses and other liabilities	$ 17	$ 8