Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
General Obligation Bonds [Member] | IOWA
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	14	16
Amortized cost	$ 20,156,969	$ 17,946,059
Fair value	20,446,655.0	17,444,045.0
Average exposure per issuer (fair value)	1,460,475	1,090,253
General Obligation Bonds [Member] | MISSOURI
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	11
Amortized cost	8,424,928
Fair value	8,426,047.0
Average exposure per issuer (fair value)	766,004
General Obligation Bonds [Member] | ILLINOIS
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	10	12
Amortized cost	22,447,799	15,063,325
Fair value	22,784,638.0	15,264,718.0
Average exposure per issuer (fair value)	2,278,464	1,272,060
General Obligation Bonds [Member] | Other States [Member]
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	42	56
Amortized cost	16,838,719	22,166,026
Fair value	17,110,831.0	21,512,582.0
Average exposure per issuer (fair value)	407,401	384,153
General Obligation Bonds [Member]
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	77	84
Amortized cost	67,868,415	55,175,410
Fair value	68,768,171.0	54,221,345.0
Average exposure per issuer (fair value)	893,093	645,492
Revenue Bonds [Member] | IOWA
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	20	17
Amortized cost	59,417,246	47,903,572
Fair value	60,402,941.0	46,257,997.0
Average exposure per issuer (fair value)	3,020,147	2,721,059
Revenue Bonds [Member] | MISSOURI
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	30	21
Amortized cost	62,358,276	42,085,249
Fair value	62,584,516.0	40,054,613.0
Average exposure per issuer (fair value)	2,086,151	1,907,363
Revenue Bonds [Member] | Other States [Member]
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	4	5
Amortized cost	8,295,311	9,009,148
Fair value	8,449,900.0	8,693,222.0
Average exposure per issuer (fair value)	2,112,475	1,738,644
Revenue Bonds [Member] | INDIANA
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	8	7
Amortized cost	17,991,200	15,020,000
Fair value	17,925,721.0	14,324,717.0
Average exposure per issuer (fair value)	2,240,715	2,046,388
Revenue Bonds [Member] | KANSAS
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	2	2
Amortized cost	12,307,866	11,022,382
Fair value	12,332,528.0	9,997,068.0
Average exposure per issuer (fair value)	6,166,264	4,998,534
Revenue Bonds [Member]
Note 3 - Investment Securities (Details) - Amoritized Cost and Fair Values of General Obligation Bonds by Issuer's State [Line Items]
Number of issuers	64	52
Amortized cost	160,369,899	125,040,351
Fair value	161,695,606.0	119,327,617.0
Average exposure per issuer (fair value)	$ 2,526,494	$ 2,294,762