Note 2 - Sales/Mergers/Acquisitions - Pro Forma Combined Operating Results (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares
Springfield Bancshares
Net interest income	$ 153,229
Noninterest income	42,538
Net income	$ 49,542
Basic (in dollars per share) | $ / shares	$ 3.17
Diluted (in dollars per share) | $ / shares	$ 3.11
Bates Companies
Net interest income	$ 142,368
Noninterest income	44,455
Net income	$ 44,032
Basic (in dollars per share) | $ / shares	$ 2.98
Diluted (in dollars per share) | $ / shares	$ 2.92