Premises and Equipment - Schedule of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Land and improvements	$ 66,609	$ 55,986
Buildings and improvements	221,139	167,044
Furniture and equipment	102,171	76,870
Total cost	389,919	299,900
Accumulated depreciation and amortization	(187,437)	(132,975)
Right of use asset	58,532
Total premises and equipment, net	$ 261,014	$ 166,925