Income Taxes (Details 2) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Reserves not yet deducted for tax purposes	$ 3,905	$ 2,633
Employee compensation and benefits	383	365
Net operating loss and tax credit carryforwards	399	119
Other	765	417
Gross deferred tax assets	5,452	3,534
Valuation allowance	(418)	(66)
Deferred tax assets after valuation allowance	5,034	3,468
Deferred tax liabilities:
Intangibles and fixed assets	1,433	1,279
Deferred revenue	252	315
Deferred interest	148	162
Investment in joint ventures	135	122
Other	366	129
Gross deferred tax liabilities	2,334	2,007
Net deferred tax assets	$ 2,700	$ 1,461