INCOME TAXES - Reconciliation of Effective Income Tax Rate to Statutory Federal Rate (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory federal tax rate	21.00%	21.00%	34.00%
Increase (decrease) resulting from:
Tax exempt interest income	(4.20%)	(7.70%)	(13.00%)
Earnings from life insurance	(1.70%)	(1.70%)	(2.40%)
Disallowed interest expense	0.30%	0.80%	1.00%
Low-income housing credits and related expense	(1.30%)	(2.50%)	(4.60%)
Merger related	0.70%	0.60%	0.00%
Expense due to enactment of federal tax reform legislation	0	0	0.212
Other	(1.00%)	0.90%	(1.30%)
Effective income tax rate	13.80%	11.40%	34.90%