Note 11 - Fair Value of Financial Instruments - Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Securities available for sale, fair value	$ 825,475	$ 822,655
Fair Value, Recurring [Member]
Assets:
Total assets	825,631	838,616
Liabilities:
Financial and Nonfinancial Liabilities, Fair Value Disclosure	74,898	44,088
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Total assets	12,206	11,586
Liabilities:
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Total assets	812,107	825,774
Liabilities:
Financial and Nonfinancial Liabilities, Fair Value Disclosure	30,988	2,239
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets:
Total assets	1,318	1,256
Liabilities:
Financial and Nonfinancial Liabilities, Fair Value Disclosure	43,910	41,849
Collateralized Mortgage Backed Securities [Member]
Assets:
Securities available for sale, fair value	579,010	557,953
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member]
Assets:
Securities available for sale, fair value	579,010	557,953
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Securities available for sale, fair value	0	0
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Securities available for sale, fair value	579,010	557,953
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets:
Securities available for sale, fair value	0	0
Other Securities [Member]
Assets:
Securities available for sale, fair value	1,318	1,256
Other Securities [Member] \| Fair Value, Recurring [Member]
Assets:
Securities available for sale, fair value	246,465	264,702
Other Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Securities available for sale, fair value	12,206	11,586
Other Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Securities available for sale, fair value	232,941	251,860
Other Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets:
Securities available for sale, fair value	1,318	1,256
Interest Rate Swap [Member] \| Fair Value, Recurring [Member]
Assets:
Interest Rate Swaps, Net Amount	156	15,961
Liabilities:
Interest Rate Swaps, Net Amount	30,988	2,239
Interest Rate Swap [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Interest Rate Swaps, Net Amount	0	0
Liabilities:
Interest Rate Swaps, Net Amount	0	0
Interest Rate Swap [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Interest Rate Swaps, Net Amount	156	15,961
Liabilities:
Interest Rate Swaps, Net Amount	30,988	2,239
Interest Rate Swap [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets:
Interest Rate Swaps, Net Amount	0	0
Liabilities:
Interest Rate Swaps, Net Amount	0	0
Junior Subordinated Debentures [Member] \| Fair Value, Recurring [Member]
Liabilities:
Borrowings	43,910	41,849
Junior Subordinated Debentures [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Liabilities:
Borrowings	0	0
Junior Subordinated Debentures [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Liabilities:
Borrowings	0	0
Junior Subordinated Debentures [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Liabilities:
Borrowings	$ 43,910	$ 41,849

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

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