Fair Value of Assets and Liabilities (Fair value on recurring basis) (Details 1) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets:
Available-for-Sale	$ 2,619,003	$ 2,007,942
Loans Held for Sale	39,062	10,987
Derivative Assets	28,931	14,604
US Government-sponsored Enterprises Debt Securities [Member]
Assets:
Available-for-Sale		56
Fair Value, Recurring [Member]
Assets:
Available-for-Sale	2,619,003	2,007,942
Loans Held for Sale	39,062	10,987
Mortgage Servicing Rights	1,126	1,290
Other Assets	41,464	31,871
Derivative Assets	28,931	14,604
Total Assets Measured at Fair Value on a Recurring Basis	2,729,586	2,066,694
Liabilities:
Derivative Liabilities	6,377	9,747
Total Liabilities Measured at Fair Value on a Recurring Basis	6,377	9,747
Fair Value, Recurring [Member] \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale	221,131	392,401
Fair Value, Recurring [Member] \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale	55,097	563,996
Fair Value, Recurring [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Assets:
Available-for-Sale	22,147
Fair Value, Recurring [Member] \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale	336,321	223,140
Fair Value, Recurring [Member] \| Mortgage-Backed Securities
Assets:
Available-for-Sale	1,984,307	828,349
Fair Value, Recurring [Member] \| Residential - Government Agencies
Assets:
Available-for-Sale	1,172,826	190,442
Fair Value, Recurring [Member] \| Residential - U.S. Government Sponsored Enterprises
Assets:
Available-for-Sale	586,761	578,527
Fair Value, Recurring [Member] \| Commercial - Government Agencies
Assets:
Available-for-Sale	224,720	59,380
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Available-for-Sale	1,155	972
Loans Held for Sale	0	0
Mortgage Servicing Rights	0	0
Other Assets	41,464	31,871
Derivative Assets	0	0
Total Assets Measured at Fair Value on a Recurring Basis	42,619	32,843
Liabilities:
Derivative Liabilities	0	0
Total Liabilities Measured at Fair Value on a Recurring Basis	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale	1,155	972
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| US Government-sponsored Enterprises Debt Securities [Member]
Assets:
Available-for-Sale	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Mortgage-Backed Securities
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Residential - Government Agencies
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Residential - U.S. Government Sponsored Enterprises
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Commercial - Government Agencies
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Assets:
Available-for-Sale	2,617,848	2,006,970
Loans Held for Sale	39,062	10,987
Mortgage Servicing Rights	0	0
Other Assets	0	0
Derivative Assets	308	812
Total Assets Measured at Fair Value on a Recurring Basis	2,657,218	2,018,769
Liabilities:
Derivative Liabilities	327	371
Total Liabilities Measured at Fair Value on a Recurring Basis	327	371
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale	219,976	391,429
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale	55,097	563,996
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| US Government-sponsored Enterprises Debt Securities [Member]
Assets:
Available-for-Sale	22,147
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale	336,321	223,140
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Mortgage-Backed Securities
Assets:
Available-for-Sale	1,984,307	828,349
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Residential - Government Agencies
Assets:
Available-for-Sale	1,172,826	190,442
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Residential - U.S. Government Sponsored Enterprises
Assets:
Available-for-Sale	586,761	578,527
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) \| Commercial - Government Agencies
Assets:
Available-for-Sale	224,720	59,380
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3)
Assets:
Available-for-Sale	0	0
Loans Held for Sale	0	0
Mortgage Servicing Rights	1,126	1,290
Other Assets	0	0
Derivative Assets	28,623	13,792
Total Assets Measured at Fair Value on a Recurring Basis	29,749	15,082
Liabilities:
Derivative Liabilities	6,050	9,376
Total Liabilities Measured at Fair Value on a Recurring Basis	6,050	9,376
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| US Government-sponsored Enterprises Debt Securities [Member]
Assets:
Available-for-Sale	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Mortgage-Backed Securities
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Residential - Government Agencies
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Residential - U.S. Government Sponsored Enterprises
Assets:
Available-for-Sale	0	0
Fair Value, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) \| Commercial - Government Agencies
Assets:
Available-for-Sale	$ 0	$ 0

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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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 of financial and nonfinancial obligations.

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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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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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