Capital Requirements and Other Regulatory Matters - Summary of Capital Amounts and Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
First NBC Bank Holding Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier one leverage capital, Actual Amount	$ 375,355	$ 243,791
Tier one risk based capital, Actual Amount	375,355	243,791
Total risk based capital, Actual Amount	407,648	270,810
Tier one leverage capital, Actual Ratio	11.76%	9.04%
Tier one risk based capital, Actual Ratio	13.26%	11.26%
Total risk based capital, Actual Ratio	14.40%	12.51%
Tier one leverage capital, Capital Adequacy Purposes	127,625	107,814
Tier one risk based capital, Capital Adequacy Purposes	113,254	86,592
Total risk based capital, Capital Adequacy Purposes	226,508	173,184
Tier one leverage capital, Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier one risk based capital, Capital Adequacy Purposes Ratio	4.00%	4.00%
Total risk based capital, Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio
First NBC Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier one leverage capital, Actual Amount	349,104	256,848
Tier one risk based capital, Actual Amount	349,104	256,848
Total risk based capital, Actual Amount	381,396	283,867
Tier one leverage capital, Actual Ratio	10.96%	9.91%
Tier one risk based capital, Actual Ratio	12.34%	11.88%
Total risk based capital, Actual Ratio	13.48%	13.13%
Tier one leverage capital, Capital Adequacy Purposes	127,435	103,704
Tier one risk based capital, Capital Adequacy Purposes	113,170	86,457
Total risk based capital, Capital Adequacy Purposes	226,340	172,914
Tier one leverage capital, Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier one risk based capital, Capital Adequacy Purposes Ratio	4.00%	4.00%
Total risk based capital, Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	159,294	129,630
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	169,755	129,686
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	$ 282,924	$ 216,143
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio	6.00%	6.00%
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%