Fair Value of Assets and Liabilities (Fair value on recurring basis) (Details 1) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Document Period End Date	Jun. 30, 2019
Assets:
Available-for-Sale: Fair Value	$ 2,649,949	$ 2,007,942
Loans Held for Sale	22,706	10,987
Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	62,219	563,996
Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	196
Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	349,812	223,140
Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,902,190	828,349
Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,227,930	190,442
Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	503,057	578,527
Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	171,203	59,380
Fair Value, Measurements, Recurring
Assets:
Available-for-Sale: Fair Value	2,649,949	2,007,942
Loans Held for Sale	22,706	10,987
Mortgage Servicing Rights	1,212	1,290
Other Assets	36,941	31,871
Derivatives	27,869	14,604
Total Assets Measured at Fair Value on a Recurring Basis	2,738,677	2,066,694
Liabilites:
Derivatives	8,292	9,747
Total Liabilities Measured at Fair Value on a Recurring Basis	8,292	9,747
Fair Value, Measurements, Recurring \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	335,532	392,401
Fair Value, Measurements, Recurring \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	62,219	563,996
Fair Value, Measurements, Recurring \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	196	56
Fair Value, Measurements, Recurring \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	349,812	223,140
Fair Value, Measurements, Recurring \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,902,190	828,349
Fair Value, Measurements, Recurring \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,227,930	190,442
Fair Value, Measurements, Recurring \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	503,057	578,527
Fair Value, Measurements, Recurring \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	171,203	59,380
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Assets:
Available-for-Sale: Fair Value	1,004	972
Loans Held for Sale	0	0
Mortgage Servicing Rights	0	0
Other Assets	36,941	31,871
Derivatives	0	0
Total Assets Measured at Fair Value on a Recurring Basis	37,945	32,843
Liabilites:
Derivatives	0	0
Total Liabilities Measured at Fair Value on a Recurring Basis	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	1,004	972
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets:
Available-for-Sale: Fair Value	2,648,945	2,006,970
Loans Held for Sale	22,706	10,987
Mortgage Servicing Rights	0	0
Other Assets	0	0
Derivatives	498	812
Total Assets Measured at Fair Value on a Recurring Basis	2,672,149	2,018,769
Liabilites:
Derivatives	877	371
Total Liabilities Measured at Fair Value on a Recurring Basis	877	371
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	334,528	391,429
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	62,219	563,996
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	196	56
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	349,812	223,140
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,902,190	828,349
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,227,930	190,442
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	503,057	578,527
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	171,203	59,380
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3)
Assets:
Available-for-Sale: Fair Value	0	0
Loans Held for Sale	0	0
Mortgage Servicing Rights	1,212	1,290
Other Assets	0	0
Derivatives	27,371	13,792
Total Assets Measured at Fair Value on a Recurring Basis	28,583	15,082
Liabilites:
Derivatives	7,415	9,376
Total Liabilities Measured at Fair Value on a Recurring Basis	7,415	9,376
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	$ 0	$ 0

Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]

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- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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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.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value of financial and nonfinancial obligations.

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- Definition

Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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- Definition

Fair value portion of other assets.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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