Cash and Due from Banks	12 Months Ended
Cash and Due from Banks	Dec. 31, 2016
Cash and Due from Banks [Abstract]
Cash and Due from Banks	Cash and Due from Banks Regulations of the Board of Governors of the Federal Reserve System impose uniform reserve requirements on all depository institutions with transaction accounts, such as checking accounts and NOW accounts. Reserves are maintained in the form of vault cash or balances held with the Federal Reserve Bank. First Commonwealth Bank maintained average balances of $5.1 million during 2016 and $4.6 million during 2015 with the Federal Reserve Bank.

The entire disclosure for cash and cash equivalent footnotes, which may include the types of deposits and money market instruments, applicable carrying amounts, restricted amounts and compensating balance arrangements. Cash and equivalents include: (1) currency on hand (2) demand deposits with banks or financial institutions (3) other kinds of accounts that have the general characteristics of demand deposits (4) short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments maturing within three months from the date of acquisition qualify.