Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Net operating loss carryforward - US	$ 968	$ 811
Net operating loss carryforward - Non-US	167	180
Market value difference of loan portfolio	23	102
Accruals	104	122
Tax credits	806	789
Other	151	157
Total deferred tax assets before valuation allowance	2,219	2,161
Less: valuation allowance	(270)	(326)
Total deferred tax assets	1,949	1,835
Deferred tax liabilities
Depreciable assets	2,020	1,619
Deferred acquisition costs	134	130
Other	103	125
Total deferred tax liabilities	2,257	1,874
Net deferred tax liability	(308)	$ (39)
Tax Year 2039 [Member]
Deferred tax assets
Net operating loss carryforward - US	180
Net operating loss carryforward - Non-US	120
Tax credits	806
Expiring Indefinitely [Member]
Deferred tax assets
Net operating loss carryforward - US	788
Net operating loss carryforward - Non-US	$ 47