Mergers and Acquisitions - Business Acquisition Pro Forma Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($) $ / shares
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 790,391
Net income	171,850
Net income available to common stockholders	$ 163,809
Earnings per common share - basic \| $ / shares	$ 0.78
Earnings per common share - diluted \| $ / shares	$ 0.78
F.N.B. Corporation [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 660,632
Net income	159,649
Net income available to common stockholders	$ 151,608
Earnings per common share - basic \| $ / shares	$ 0.87
Earnings per common share - diluted \| $ / shares	$ 0.86
Metro Bancorp Inc [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 134,003
Net income	20,215
Net income available to common stockholders	$ 20,135
Earnings per common share - basic \| $ / shares	$ 1.42
Earnings per common share - diluted \| $ / shares	$ 1.40
Proforma Adjustments [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ (4,244)
Net income	(8,014)
Net income available to common stockholders	$ (7,934)

Business Acquisition Pro Forma Information [Line Items]

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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=65885119&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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