Note 11 - Regulatory Matters (Detail) - Actual Capital Amounts and Ratios (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Princeton National Bancorp Inc [Member]
Actual Capital Amount (in Dollars)	$ (7,736)	$ (3,418)
Actual Capital Ratio	(1.31%)	(0.50%)
Minimum Capital Requirement Amount (in Dollars)	47,270	55,204
Minimum Capital Requirement Ratio	8.00%	8.00%
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Amount (in Dollars)	70,830	81,306
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Ratio	12.00%	12.00%
Actual Tier 1 Capital to Risk-Weighted Assets Amount (in Dollars)	(7,736)	(3,418)
Actual Tier 1 Capital to Risk-Weighted Assets Ratio	(1.31%)	(0.50%)
Minimum Capital Requirement Tier 1 Capital to Risk-Weighted Assets Amount (in Dollars)	23,610	27,102
Minimum Capital Requirement Tier 1 Capital to Risk-Weighted Assets Ratio	4.00%	4.00%
Actual Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	(7,736)	(3,418)
Actual Tier 1 Capital (to average adjusted assets) Ratio	(0.80%)	(0.32%)
Minimum Capital Requirement Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	38,740	42,365
Minimum Capital Requirement Tier 1 Capital (to average adjusted assets) Ratio	4.00%	4.00%
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	77,480	84,729
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Tier 1 Capital (to average adjusted assets) Ratio	8.00%	8.00%
Citizens First National Bank [Member]
Actual Capital Amount (in Dollars)	25,496	31,554
Actual Capital Ratio	4.33%	4.60%
Minimum Capital Requirement Amount (in Dollars)	47,215	54,892
Minimum Capital Requirement Ratio	8.00%	8.00%
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Amount (in Dollars)	70,823	82,339
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Ratio	12.00%	12.00%
Actual Tier 1 Capital to Risk-Weighted Assets Amount (in Dollars)	17,932	22,707
Actual Tier 1 Capital to Risk-Weighted Assets Ratio	3.05%	3.31%
Minimum Capital Requirement Tier 1 Capital to Risk-Weighted Assets Amount (in Dollars)	23,608	27,446
Minimum Capital Requirement Tier 1 Capital to Risk-Weighted Assets Ratio	4.00%	4.00%
Actual Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	17,932	22,707
Actual Tier 1 Capital (to average adjusted assets) Ratio	1.85%	2.14%
Minimum Capital Requirement Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	38,737	42,354
Minimum Capital Requirement Tier 1 Capital (to average adjusted assets) Ratio	4.00%	4.00%
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Tier 1 Capital (to average adjusted assets) Amount (in Dollars)	$ 77,474	$ 84,718
Minimum To Be Well- Capitalized Under Prompt Corrective Action Provisions Tier 1 Capital (to average adjusted assets) Ratio	8.00%	8.00%