Mergers and Acquisitions - Business Acquisition Pro Forma Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 280,762	$ 259,784
Net income	71,978	39,613
Net income available to common stockholders	$ 69,968	$ 37,603
Earnings per common share - basic	$ 0.22	$ 0.12
Earnings per common share - diluted	$ 0.22	$ 0.12
F.N.B. Corporation [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 206,969	$ 186,398
Net income	51,253	26,132
Net income available to common stockholders	$ 49,243	$ 24,122
Earnings per common share - basic	$ 0.23	$ 0.12
Earnings per common share - diluted	$ 0.23	$ 0.12
Yadkin Financial Corporation (YDKN) [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ 74,574	$ 74,709
Net income	22,435	15,447
Net income available to common stockholders	$ 22,435	$ 15,447
Earnings per common share - basic	$ 0.43	$ 0.30
Earnings per common share - diluted	$ 0.43	$ 0.30
Proforma Adjustments [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue (net interest income and non-interest income)	$ (781)	$ (1,323)
Net income	(1,710)	(1,966)
Net income available to common stockholders	$ (1,710)	$ (1,966)