Deposits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Banking and Thrift1 [Abstract]
Cash amount that exceeded federally insured limits	$ 6,400.0	$ 5,100.0
Increase in demand accounts	1,600.0
Increase savings accounts	765.5
Decrease in certificates of deposit	673.2
Decrease brokered deposits	$ 141.2

Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116652737&loc=d3e64164-112818

Name:	us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant