The cumulative amount of the reporting entity's undistributed earnings or deficit.

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

Basis of Presentation (Details) $ in Thousands		9 Months Ended
Basis of Presentation (Details) $ in Thousands	Jan. 01, 2020 USD ($)	Sep. 30, 2021 USD ($) segment subsidiary	Dec. 31, 2020 USD ($)
Basis of presentation
Number of operating segments \| segment		1
Number of active operating bank subsidiaries \| subsidiary		5
Retained earnings		$ 2,414,183	$ 2,289,626
ASU 2016-13 \| Adjustment
Basis of presentation
Percentage of allowance for loan losses	17.20%
Retained earnings	$ 8,300