Securities (Amortized Cost and Fair Value of Debt Securities Held to Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	$ 1,307,701	$ 1,357,170
Securities Held to Maturity, Gross Unrealized Gains	79,070	110,413
Securities Held to Maturity, Gross Unrealized Losses	804	2
Securities Held to Maturity, Fair Value	1,385,967	1,467,581
Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	617,289	627,019
Securities Held to Maturity, Gross Unrealized Gains	39,989	51,408
Securities Held to Maturity, Gross Unrealized Losses	211	2
Securities Held to Maturity, Fair Value	657,067	678,425
Residential Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	47,330	21,951
Securities Held to Maturity, Gross Unrealized Gains	985	1,469
Securities Held to Maturity, Gross Unrealized Losses	243
Securities Held to Maturity, Fair Value	48,072	23,420
Commercial Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	573,854	549,686
Securities Held to Maturity, Gross Unrealized Gains	36,614	54,587
Securities Held to Maturity, Gross Unrealized Losses	350
Securities Held to Maturity, Fair Value	610,118	604,273
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	69,228	158,514
Securities Held to Maturity, Gross Unrealized Gains	1,482	2,949
Securities Held to Maturity, Fair Value	$ 70,710	$ 161,463

Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

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- Definition

Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

+ References

No definition available.

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=SL120269820-111563

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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