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Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Allowance for credit loss	$ 45,444	$ 49,395	$ 45,444	$ 49,395	$ 46,365	$ 52,420	$ 46,316	$ 30,482
Unfunded Commitments [Member]
Commitments And Contingencies [Line Items]
Credit loss (benefit) expense	(206)	$ 461	(1,200)	$ 959
Unfunded Commitments [Member] | Other Liabilities [Member]
Commitments And Contingencies [Line Items]
Allowance for credit loss	$ 1,900		$ 1,900			$ 3,100

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
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