Securities (Amortized Cost and Fair Value of Debt Securities Held to Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	$ 1,357,170	$ 1,568,009
Securities Held to Maturity, Gross Unrealized Gains	110,413	44,103
Securities Held to Maturity, Gross Unrealized Losses	2	1,108
Securities Held to Maturity, Fair Value	1,467,581	1,611,004
U.S. Treasury And Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost		50,000
Securities Held to Maturity, Gross Unrealized Gains		3
Securities Held to Maturity, Fair Value		50,003
Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	627,019	641,019
Securities Held to Maturity, Gross Unrealized Gains	51,408	27,146
Securities Held to Maturity, Gross Unrealized Losses	2	69
Securities Held to Maturity, Fair Value	678,425	668,096
Residential Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	21,951	29,687
Securities Held to Maturity, Gross Unrealized Gains	1,469	883
Securities Held to Maturity, Fair Value	23,420	30,570
Commercial Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	549,686	539,371
Securities Held to Maturity, Gross Unrealized Gains	54,587	12,474
Securities Held to Maturity, Gross Unrealized Losses		581
Securities Held to Maturity, Fair Value	604,273	551,264
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Gross Amortized Cost	158,514	307,932
Securities Held to Maturity, Gross Unrealized Gains	2,949	3,597
Securities Held to Maturity, Gross Unrealized Losses		458
Securities Held to Maturity, Fair Value	$ 161,463	$ 311,071

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=121645371&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=121645371&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

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