NOTE 9 - BUSINESS SEGMENT INFORMATION - Selected Financial Information on the Company's Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Total revenue	$ 76,723			$ 58,640			$ 212,063	$ 156,437
Net interest income	40,719			38,314			115,640	102,801
Provision	2,012			6,206			6,087	11,046
Net income (loss)	15,095	$ 13,504	$ 12,918	8,809	$ 10,445	$ 10,550	41,517	29,804
Goodwill	77,748			73,618			77,748	73,618	$ 77,832
Intangibles	15,529			16,137			15,529	16,137	17,450
Total assets	5,292,382			4,792,732			5,292,382	4,792,732	$ 4,949,710
Intersegment Eliminations [Member]
Total revenue	(22,036)			(12,707)			(54,563)	(38,450)
Net interest income				5				5
Net income (loss)	(19,280)			(12,467)			(50,897)	(37,832)
Total assets	(619,830)			(537,349)			(619,830)	(537,349)
Commercial Banking Segment [Member] | Quad City Bank and Trust Company [Member] | Operating Segments [Member]
Total revenue	21,230			17,322			60,148	49,812
Net interest income	13,357			12,218			38,129	36,629
Provision	948			409			2,941	2,784
Net income (loss)	4,870			4,827			13,560	13,796
Goodwill	3,223			3,223			3,223	3,223
Total assets	1,642,950			1,579,327			1,642,950	1,579,327
Commercial Banking Segment [Member] | Cedar Rapids Bank and Trust [Member] | Operating Segments [Member]
Total revenue	25,707			16,800			68,526	49,301
Net interest income	11,478			10,833			32,671	32,149
Provision	150			453			875	1,682
Net income (loss)	7,900			4,869			19,928	14,191
Goodwill	14,980			14,979			14,980	14,979
Intangibles	2,810			3,313			2,810	3,313
Total assets	1,592,896			1,354,293			1,592,896	1,354,293
Commercial Banking Segment [Member] | Community State Bank [Member] | Operating Segments [Member]
Total revenue	11,596			8,889			30,596	25,459
Net interest income	8,894			7,101			23,154	20,579
Provision	150			20			451	817
Net income (loss)	3,482			2,533			7,845	6,560
Goodwill	9,888			9,888			9,888	9,888
Intangibles	4,154			4,852			4,154	4,852
Total assets	801,596			734,536			801,596	734,536
Commercial Banking Segment [Member] | SPRINGFIELD BANCSHARES, INC | Operating Segments [Member]
Total revenue	8,351			7,360			23,396	7,360
Net interest income	5,056			5,701			15,707	5,701
Provision	276			475			1,261	475
Net income (loss)	2,116			2,198			5,848	2,197
Goodwill	45,975			45,528			45,975	45,528
Intangibles	7,034			7,972			7,034	7,972
Total assets	693,898			623,520			693,898	623,520
Wealth Management Segment [Member] | Operating Segments [Member]
Total revenue	4,122			3,255			12,599	9,560
Net income (loss)	926			768			2,667	2,336
Other Segments [Member] | Operating Segments [Member]
Total revenue	27,753			17,721			71,361	53,395
Net interest income	1,934			2,456			5,979	7,738
Provision	488			4,849			559	5,288
Net income (loss)	15,081			6,081			42,566	28,556
Goodwill	3,682						3,682
Intangibles	1,531						1,531
Total assets	$ 1,180,872			$ 1,038,405			$ 1,180,872	$ 1,038,405