Organization and Summary of Significant Accounting Policies - VIEs and Cash and Due from Banks (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Cash and Due from Banks
Average cash reserves required with Federal Reserve Bank	$ 18.4	$ 67.4
Included in other liabilities \| VIEs, not primary beneficiary
Variable Interest Entities
Unfunded commitments to fund low-income housing partnerships	$ 89.0	$ 102.8

Amount of commitment or contingent commitments to qualified affordable housing project investments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985

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