Goodwill and Core Deposit Intangibles - Intangible Assets Narrative (Details) - Core Deposits Intangibles - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life (in years)	10 years
Proceeds from sale of custodial rights	$ 6.2
Reductions due to sale of accounts	$ 0.0	$ (3.2)

Finite-Lived Intangible Assets, Increase (Decrease) From Sale Of Accounts

No definition available.

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

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.

+ Details

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- Definition

The cash inflow from disposal of asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

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- Details

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