Income Taxes (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Reserves not yet deducted for tax purposes	$ 2,612	$ 2,724
Employee compensation and benefits	360	403
Deferred Tax Assets, Other	431	409
Gross deferred tax assets	3,403	3,536
Valuation allowance	(61)	(46)
Deferred tax assets after valuation allowance	3,342	3,490
Deferred tax liabilities:
Intangibles and fixed assets	1,083	1,057
Deferred revenue	435	306
Deferred interest	171	183
Investment in joint ventures	137	137
Other	210	269
Gross deferred tax liabilities	2,036	1,952
Net deferred tax assets	$ 1,306	$ 1,538