Fair Value - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Assets
Derivative financial instruments	$ 14,600
Securities available for sale	1,717,276	$ 1,577,999	$ 1,517,067
Liabilities
Derivative financial instruments	15,800
Government-sponsored entities debt
Assets
Securities available for sale	66,529	47,613	48,251
State and municipal obligations
Assets
Securities available for sale	182,146	223,816	200,768
Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	30,332	35,107	34,727
Changes in fair value of assets
Changes in hierarchy classifications of Level 3 liabilities	0
Recurring basis
Assets
Derivative financial instruments	17,587	8,848	5,090
Loans held for sale	47,796	36,968	22,925
Securities available for sale	1,717,276	1,577,999	1,517,067
Mortgage servicing rights	30,332	35,107	34,727
Fair value of Assets, Total	1,812,991	1,658,922	1,579,809
Liabilities
Derivative financial instruments	30,286	8,097	4,421
Recurring basis \| Government-sponsored entities debt
Assets
Securities available for sale	66,529	47,613	48,251
Recurring basis \| State and municipal obligations
Assets
Securities available for sale	182,146	223,816	200,768
Recurring basis \| Mortgage-backed securities
Assets
Securities available for sale	1,468,601	1,306,570	1,268,048
Recurring basis \| Significant Other Observable Inputs (Level 2)
Assets
Derivative financial instruments	17,587	8,848	5,090
Loans held for sale	47,796	36,968	22,925
Securities available for sale	1,717,276	1,577,999	1,517,067
Fair value of Assets, Total	1,782,659	1,623,815	1,545,082
Liabilities
Derivative financial instruments	30,286	8,097	4,421
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Government-sponsored entities debt
Assets
Securities available for sale	66,529	47,613	48,251
Recurring basis \| Significant Other Observable Inputs (Level 2) \| State and municipal obligations
Assets
Securities available for sale	182,146	223,816	200,768
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Mortgage-backed securities
Assets
Securities available for sale	1,468,601	1,306,570	1,268,048
Recurring basis \| Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	30,332	35,107	34,727
Fair value of Assets, Total	30,332	35,107	$ 34,727
Changes in fair value of assets
Fair value of assets at the beginning of the period	34,727	31,119
Servicing assets that resulted from transfers of financial assets	2,558	3,112
Change in unrealized loss recognized in other comprehensive income	0	0
Changes in fair value assets due to valuation inputs or assumptions	(4,924)	2,945
Changes in fair value due to decay	2,029	2,069
Fair value of assets at the end of the period	30,332	35,107
Unrealized losses included in accumulated other comprehensive income related to Level 3 financial assets and liabilities	$ 0	$ 0

Represents the amount of servicing assets that resulted from transfers of financial assets.

No definition available.

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- Definition

The element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, the element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. The item represents residential mortgage servicing rights as presented on the statement of financial position which are due to the entity as of the balance sheet date.

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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- References

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
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-SubTopic 10
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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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- Definition

Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

+ References

No definition available.

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

No definition available.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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