Mergers and Acquisitions - Business Acquisition Pro Forma Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($) $ / shares
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 192,668
Net income	44,062
Net income available to common stockholders	$ 42,052
Earnings per common share - basic \| $ / shares	$ 0.20
Earnings per common share - diluted \| $ / shares	$ 0.20
F.N.B. Corporation [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 160,103
Net income	40,343
Net income available to common stockholders	$ 38,333
Earnings per common share - basic \| $ / shares	$ 0.22
Earnings per common share - diluted \| $ / shares	$ 0.22
Metro Bancorp Inc [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 33,626
Net income	5,722
Net income available to common stockholders	$ 5,702
Earnings per common share - basic \| $ / shares	$ 0.40
Earnings per common share - diluted \| $ / shares	$ 0.39
Proforma Adjustments [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ (1,061)
Net income	(2,003)
Net income available to common stockholders	$ (1,983)

Business Acquisition Pro Forma Information [Line Items]

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- Definition

The pro forma net income or loss available to common shareholders for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

No definition available.

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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