BORROWINGS - Junior Subordinated Debt Trusts (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 101	$ 111
Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	106
Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	4
F.N.B. Statutory Trust II [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
Interest Rate	4.26%
F.N.B. Statutory Trust II [Member] | LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.65%
F.N.B. Statutory Trust II [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
F.N.B. Statutory Trust II [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
Omega Financial Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 27
Interest Rate	4.97%
Omega Financial Capital Trust I [Member] | LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	2.19%
Omega Financial Capital Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 26
Omega Financial Capital Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
Yadkin Valley Statutory Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 21
Interest Rate	3.93%
Yadkin Valley Statutory Trust I [Member] | LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.32%
Yadkin Valley Statutory Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 25
Yadkin Valley Statutory Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
FNB Financial Services Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
Interest Rate	4.05%
FNB Financial Services Capital Trust I [Member] | LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.46%
FNB Financial Services Capital Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 25
FNB Financial Services Capital Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
Crescent Financial Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 9
Interest Rate	5.89%
Crescent Financial Capital Trust I [Member] | LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	3.10%
Crescent Financial Capital Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 8
Crescent Financial Capital Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 0