Subordinated Debentures Schedule of Subordinated Debentures Outstanding (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Subordinated debentures	$ 128,385	$ 128,305
First Commonwealth Bank 2033 [Member]
Debt Instrument [Line Items]
Subordinated debentures	49,445	49,411
First Commonwealth Capital Trust II [Member]
Debt Instrument [Line Items]
Subordinated debentures	30,929	30,929
First Commonwealth Capital Trust III [Member]
Debt Instrument [Line Items]
Subordinated debentures	41,238	41,238
First Commonwealth Financial Corporation
Debt Instrument [Line Items]
Subordinated debentures	$ 6,773	$ 6,727