GOODWILL AND OTHER INTANGIBLES - Gross Amount and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2012
Core Deposits [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 51,664	$ 51,664
Accumulated amortization	(47,568)	(47,329)
Net carrying amount	$ 4,096	$ 4,335
Remaining amortization period	5 years 9 months 18 days	6 years
Purchased Credit Card Relationship Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount			$ 24,500
Purchased Credit Card Relationship Intangible [Member] | Credit Card [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 24,465	$ 24,465
Accumulated amortization	(19,285)	(18,763)
Net carrying amount	$ 5,180	$ 5,702
Remaining amortization period	2 years 7 months 6 days	2 years 10 months 24 days
Customer Relationships [Member] | Insurance Customer Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 1,067	$ 1,067
Accumulated amortization	(483)	(445)
Net carrying amount	$ 584	$ 622
Remaining amortization period	3 years 9 months 18 days	4 years