New Accounting Standards (Cumulative Effect of Changes for the Adoption of ASU 2016-02) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Other assets		$ 2,634	$ 2,046
Operating lease right-of-use asset	$ 596
Liabilities
Accrued expenses and other liabilities		3,542	$ 2,954
Operating lease liability	$ 665
ASU 2016-02 [Member]
Assets
Operating lease right-of-use asset		596
Prepaid rent and initial direct costs		8
Liabilities
Operating lease liability		662
Deferred rent and lease incentives		74
ASU 2016-02 [Member] | Adjustments [Member]
Assets
Other assets		588
Liabilities
Accrued expenses and other liabilities		$ 588