Leasing Activity Leasing Activity, Investment in Lease Financing (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Investment in Lease Financing [Line Items]
Lease receivables	$ 17,735	$ 17,735
Residual asset values	4,244	4,244
Unearned income	(2,655)	(2,655)
Lease financing	19,324	19,324
Leasing Activity Disclosures Textual [Abstract]
Net investment in leveraged leases, lessor	2,100	2,100
Operating lease assets, lessor	9,489	9,489	$ 9,444
Assets Leased to Others [Member]
Leasing Activity Disclosures Textual [Abstract]
Operating lease assets, lessor	8,663	8,663	$ 9,036
Accumulated depreciation, Operating lease assets, lessor	3,200	3,200
Depreciation, Operating lease assets, lessor	$ 219	$ 448