Note 11 - Fair Value of Financial Instruments - Carrying Amounts and Estimated Fair Values of Selected Financial Instruments (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Securities held-to-maturity, amortized cost	$ 60,186,000	$ 32,018,000
Securities available for sale, fair value	808,653,000	822,655,000
Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	1,635,000	1,001,000
Interest rate swaps	4,540,000	2,239,000
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	7,944,000	7,953,000
Securities available for sale, fair value	554,481,000	557,953,000
Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	52,242,000	24,065,000
Securities available for sale, fair value	254,172,000	264,702,000
Reported Value Measurement [Member]
Cash and due from banks	56,484,000	118,561,000
Loans	5,638,413,000	5,551,484,000
FHLB-NY stock	63,029,000	57,282,000
Accrued interest receivable	26,552,000	25,485,000
Deposits	4,877,917,000	4,960,784,000
Liabilities, Fair Value	1,371,890,000	1,250,843,000
Accrued interest payable	7,106,000	5,890,000
Reported Value Measurement [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	1,635,000	15,961,000
Interest rate swaps	20,147,000	2,239,000
Reported Value Measurement [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	7,944,000	7,953,000
Securities available for sale, fair value	554,481,000	557,953,000
Reported Value Measurement [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	52,242,000	24,065,000
Securities available for sale, fair value	254,172,000	264,702,000
Estimate of Fair Value Measurement [Member]
Cash and due from banks	56,484,000	118,561,000
Loans	5,625,107,000	5,496,266,000
FHLB-NY stock	63,029,000	57,282,000
Accrued interest receivable	26,563,000	25,485,000
Deposits	4,882,473,000	4,955,077,000
Liabilities, Fair Value	1,371,479,000	1,241,745,000
Accrued interest payable	7,106,000	5,890,000
Estimate of Fair Value Measurement [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	1,635,000	15,961,000
Interest rate swaps	20,147,000	2,239,000
Estimate of Fair Value Measurement [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	8,038,000	7,366,000
Securities available for sale, fair value	554,481,000	557,953,000
Estimate of Fair Value Measurement [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	54,131,000	22,508,000
Securities available for sale, fair value	254,172,000	264,702,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	56,484,000	118,561,000
Loans	0	0
FHLB-NY stock	0	0
Accrued interest receivable	34,000	54,000
Deposits	3,333,800,000	3,397,474,000
Liabilities, Fair Value	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	0	0
Interest rate swaps	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	12,042,000	11,586,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash and due from banks	0	0
Loans	0	0
FHLB-NY stock	63,029,000	57,282,000
Accrued interest receivable	3,055,000	2,756,000
Deposits	1,548,673,000	1,557,603,000
Liabilities, Fair Value	1,328,065,000	1,199,896,000
Accrued interest payable	7,106,000	5,890,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	1,635,000	15,961,000
Interest rate swaps	20,147,000	2,239,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	8,038,000	7,366,000
Securities available for sale, fair value	554,481,000	557,953,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	240,827,000	251,860,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash and due from banks	0	0
Loans	5,625,107,000	5,496,266,000
FHLB-NY stock	0	0
Accrued interest receivable	23,474,000	22,675,000
Deposits	0	0
Liabilities, Fair Value	43,414,000	41,849,000
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	0	0
Interest rate swaps	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	54,131,000	22,508,000
Securities available for sale, fair value	$ 1,303,000	$ 1,256,000

Fair value portion of accrued interest payable.

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Fair value portion of accrued interest receivable.

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

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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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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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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