Regulatory Matters - Schedule of Bank's Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Banking And Thrift [Abstract]
Total capital (to risk-weighted assets), Actual Amount	$ 59,370	$ 55,900
Tier 1 capital (to risk-weighted assets), Actual Amount	46,793	43,328
Tier 1 common equity capital (to risk-weighted assets), Actual Amount	46,793	43,328
Tier 1 capital (to total assets), Actual Amount	$ 46,793	$ 43,328
Total capital (to risk-weighted assets), Actual Ratio	12.47%	12.07%
Tier 1 capital (to risk-weighted assets), Actual Ratio	9.83%	9.35%
Tier 1 common equity capital (to risk-weighted assets), Actual Ratio	9.83%	9.35%
Tier 1 capital (to total assets), Actual Ratio	8.10%	7.87%
Total capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 38,083	$ 37,064
Tier 1 capital (to risk-weighted assets), Minimum Capital Requirement Amount	28,562	27,798
Tier 1 common equity capital (to risk-weighted assets), Minimum Capital Requirement Amount	21,421	20,848
Tier 1 capital (to total assets), Minimum Capital Requirement Amount	$ 23,110	$ 22,023
Total capital (to risk-weighted assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Tier 1 capital (to risk-weighted assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier 1 common equity capital (to risk-weighted assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Tier 1 capital (to total assets), Minimum Capital Requirement Ratio	4.00%	4.00%
Total capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Amount	$ 47,603	$ 46,330
Tier 1 capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Amount	38,083	37,064
Tier 1 common equity capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Amount	30,942	30,114
Tier 1 capital (to total assets), To be Well Capitalized under Prompt Corrective Action Provisions Amount	$ 28,888	$ 27,528
Total capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Ratio	8.00%	8.00%
Tier 1 common equity capital (to risk-weighted assets), To be Well Capitalized under Prompt Corrective Action Provisions Ratio	6.50%	6.50%
Tier 1 capital (to total assets), To be Well Capitalized under Prompt Corrective Action Provisions Ratio	5.00%	5.00%

FIRST PRIORITY FINANCIAL CORP. 10-Q