Summary of Significant Accounting Policies and Nature of Operations - Schedule of Impact Resulted from ASU 2017-07 Adoption (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Accounting Policies [Abstract]
securities held to maturity transferred to securities available for sale	$ 0	$ 170
Salaries and employee benefits	676	685
Other	$ 127	$ 110

Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(4))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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