NOTE 8 - BUSINESS SEGMENT INFORMATION - Selected Financial Information on the Company's Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Total revenue	$ 71,246		$ 49,711		$ 135,341	$ 97,799
Net interest income	38,013		32,085		74,921	64,488
Provision	1,941		2,301		4,075	4,841
Net income (loss)	13,504	$ 12,918	10,445	$ 10,550	26,422	20,995
Goodwill	77,748		28,091		77,748	28,091	$ 77,832
Intangibles	16,089		8,470		16,089	8,470	17,450
Total assets	5,194,852		4,106,883		5,194,852	4,106,883	$ 4,949,710
Intersegment Eliminations [Member]
Total revenue	(17,870)		(13,142)		(32,528)	(25,742)
Net income (loss)	(17,167)		(12,945)		(31,617)	(25,365)
Total assets	(613,033)		(461,660)		(613,033)	(461,660)
Commercial Banking Segment [Member] | Quad City Bank and Trust Company [Member] | Operating Segments [Member]
Total revenue	20,374		16,683		38,918	32,491
Net interest income	12,632		12,290		24,771	24,410
Provision	973		1,254		1,993	2,375
Net income (loss)	4,505		4,511		8,690	8,969
Goodwill	3,223		3,223		3,223	3,223
Total assets	1,637,115		1,563,643		1,637,115	1,563,643
Commercial Banking Segment [Member] | Cedar Rapids Bank and Trust [Member] | Operating Segments [Member]
Total revenue	23,575		16,504		42,819	32,501
Net interest income	10,785		10,481		21,193	21,317
Provision	300		628		725	1,230
Net income (loss)	6,928		4,705		12,028	9,321
Goodwill	14,980		14,980		14,980	14,980
Intangibles	2,935		3,440		2,935	3,440
Total assets	1,527,521		1,345,431		1,527,521	1,345,431
Commercial Banking Segment [Member] | Community State Bank [Member] | Operating Segments [Member]
Total revenue	9,730		8,406		19,000	16,570
Net interest income	7,294		6,735		14,260	13,479
Provision	151		221		301	797
Net income (loss)	2,207		2,158		4,363	4,027
Goodwill	9,888		9,888		9,888	9,888
Intangibles	4,328		5,030		4,328	5,030
Total assets	806,704		712,139		806,704	712,139
Commercial Banking Segment [Member] | Rockford Bank and Trust [Member] | Operating Segments [Member]
Total revenue	5,659		5,120		11,255	10,118
Net interest income	3,373		3,402		6,801	6,867
Provision	32		198		71	439
Net income (loss)	786		814		1,304	1,555
Total assets	523,262		484,123		523,262	484,123
Commercial Banking Segment [Member] | SPRINGFIELD BANCSHARES, INC | Operating Segments [Member]
Total revenue	7,757				15,045
Net interest income	5,425				10,651
Provision	485				985
Net income (loss)	2,079				3,732
Goodwill	45,975				45,975
Intangibles	7,268				7,268
Total assets	671,644				671,644
Wealth Management Segment [Member] | Operating Segments [Member]
Total revenue	4,249		3,116		8,478	6,305
Net income (loss)	583		797		1,741	1,568
Other Segments [Member] | Operating Segments [Member]
Total revenue	17,772		13,024		32,354	25,556
Net interest income	(1,496)		(823)		(2,755)	(1,585)
Net income (loss)	13,583		10,405		26,181	20,920
Goodwill	3,682				3,682
Intangibles	1,558				1,558
Total assets	$ 641,639		$ 463,207		$ 641,639	$ 463,207