Note 6 - Loans and the Allowance for Loan Losses - (Details Textual) - USD ($)		6 Months Ended		12 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Loans Receivable, Unpaid Principal Balance		$ 64,300,000		$ 55,500,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	[1]	749,000		1,776,000
Loans and Leases Receivable, Net of Deferred Income		874,506,000		810,951,000
Loans and Leases Receivable, Deferred Income		1,200,000		761,000
Loans and Leases Receivable Reclassified from Overdraft		155,000		232,000
Impaired Financing Receivable, Interest Income, Accrual Method		57,000	$ 138,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		3,300,000		0
American Gateway Financial Corporation [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net		749,000		1,776,000	$ 3,634,000
American Gateway Financial Corporation [Member] | Performing Financial Instruments [Member]
Loans Receivable, Fair Value Disclosure		54,300,000		65,300,000
Loans and Leases Receivable, Net of Deferred Income		55,600,000		65,900,000
Loans and Leases Receivable, Deferred Income		$ 2,000,000		$ 2,400,000

[1] Purchased credit impaired loans are evaluated for impairment on an individual basis.