Acquisitions - Schedules of Loans Acquired (Details) - USD ($) $ in Millions	Apr. 08, 2019	Aug. 16, 2018
Idaho Independent Bank [Member]
Business Acquisition [Line Items]
Contractually required principal and interest payments	$ 24.1
Contractual cash flows not expected to be collected (“non-accretable discount”)	3.9
Cash flows expected to be collected	20.2
Interest component of cash flows expected to be collected (“accretable discount”)	3.4
Fair value of acquired credit-impaired loans	16.8
Contractually required principal and interest payments	398.7
Contractual cash flows not expected to be collected	15.2
Fair value at acquisition	$ 321.5
Inland Northwest Bank [Member]
Business Acquisition [Line Items]
Contractually required principal and interest payments		$ 27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)		4.4
Cash flows expected to be collected		23.1
Interest component of cash flows expected to be collected (“accretable discount”)		3.2
Fair value of acquired credit-impaired loans		19.9
Contractually required principal and interest payments		894.8
Contractual cash flows not expected to be collected		26.1
Fair value at acquisition		$ 693.2

Loans Acquired in Transfer, Contractually Required Payments Receivable at Acquisition

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Loans Acquired in Transfer, Nonaccretable Difference

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Loans Acquired in Transfer at Acquisition Fair Value

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The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans with deteriorating of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The amount of the loan's contractually required payments receivable in excess of the amount of its cash flows expected to be collected. This relates to loans with deteriorating of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
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Amount of cash flows expected to be collected at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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Amount of contractually required payments receivable at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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