XML 150 R135.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Capital - Additional Information (Detail) $ / shares in Units, $ in Millions | 12 Months Ended | 18 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2015 program $ / shares | Dec. 31, 2013 shares | Jan. 27, 2015 shares | Jan. 28, 2014 shares | Jan. 29, 2013 shares | Jun. 19, 2012 USD ($)
Disclosure Capital Additional Information [Abstract] |  |  |  |  |  |
Announcement of common stock repurchase program | $ |  |  |  |  |  | $ 50.0
Number of shares authorized to be repurchased |  |  | 25,000,000.0 | 25,000,000.0 | 25,000,000.0 |
Number of repurchase programs | program | 3 |  |  |  |  |
Stock repurchased (in shares) |  | 16,619,205 |  |  |  |
Average price per share | $ / shares | $ 7.55 |  |  |  |  |

X
- Definition Disclosure - Capital - Additional Information [Abstract] + References No definition available. + Details
Name: | fcf_DisclosureCapitalAdditionalInformationAbstract
Namespace Prefix: | fcf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stock Repurchase Program, Number of Repurchase Programs + References No definition available. + Details
Name: | fcf_StockRepurchaseProgramNumberofRepurchasePrograms
Namespace Prefix: | fcf_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of stock repurchase plan authorized. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
Name: | us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total cost of shares repurchased divided by the total number of shares repurchased. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details
Name: | us-gaap_TreasuryStockAcquiredAverageCostPerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration