Note 17 - Fair Values of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Securities available for sale		$ 337,366,000	$ 335,744,000
Servicing Asset at Fair Value, Amount, Ending Balance		8,400,000	8,400,000
Reported Value Measurement [Member]
Securities available for sale	[1]	337,366,000	335,744,000
Federal Home Loan Bank stock	[2]	16,022,000	11,036,000
Reported Value Measurement [Member] | Interest Rate Swap [Member]
Interest rate swap	[1]	0	2,000
Estimate of Fair Value Measurement [Member]
Securities available for sale	[1]	337,366,000	335,744,000
Federal Home Loan Bank stock	[2]	16,022,000	11,036,000
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member]
Interest rate swap	[1]	0	2,000
Fair Value, Inputs, Level 1 [Member]
Securities available for sale		0
Fair Value, Inputs, Level 1 [Member] | Reported Value Measurement [Member]
Cash		15,656,000	11,565,000
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member]
Cash		15,656,000	11,565,000
Fair Value, Inputs, Level 2 [Member]
Securities sold under agreements to repurchase		103,519,000	118,748,000
Federal Home Loan Bank advances		348,428,000	217,130,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member]
Cash equivalents		59,698,000	188,536,000
Loans held for sale		1,122,000	2,553,000
Servicing Asset at Fair Value, Amount, Ending Balance		4,436,000	5,106,000
Accrued interest receivable		9,896,000	8,770,000
Deposits		2,463,708,000	2,522,365,000
Subordinated debentures		46,199,000	45,517,000
Accrued interest payable		2,249,000	1,919,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member]
Cash equivalents		59,698,000	188,536,000
Loans held for sale		1,122,000	2,553,000
Servicing Asset at Fair Value, Amount, Ending Balance		8,444,000	8,373,000
Accrued interest receivable		9,896,000	8,770,000
Deposits		2,471,617,000	2,368,188,000
Subordinated debentures		46,543,000	45,732,000
Accrued interest payable		2,249,000	1,919,000
Fair Value, Inputs, Level 3 [Member] | Reported Value Measurement [Member]
Loans, net		2,729,583,000	2,536,498,000
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Loans, net		$ 2,711,687,000	$ 2,520,063,000

[1] See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.

[2] It is not practical to determine the fair value of FHLBI stock due to transferability restrictions.