Employee Share-based Incentives - Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cost of prior grants of RSUs, performance share units (“PSUs”) and stock appreciation rights (“SARs”) that are amortized over their applicable vesting periods	$ 278	$ 276	$ 617	$ 674
Accrual of estimated costs of share-based awards to be granted in future periods including those to full-career eligible employees	292	304	606	612
Total noncash compensation expense related to employee share-based incentive plans	$ 570	$ 580	$ 1,223	$ 1,286

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_ShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration