Business Combinations - Additional Information (Detail) $ in Thousands		3 Months Ended
	Jan. 31, 2018 USD ($)	Mar. 31, 2018 Property
Sun Bancorp, Inc.
Business Acquisition [Line Items]
Purchase accounting adjustments, assets	$ 2,044,739
Purchase accounting adjustments, loans	1,517,947
Purchase accounting adjustments, deposits	1,616,073
Total consideration paid	474,930
Cash consideration	72,400
Number of properties in lease agreement | Property		21
Core Deposits
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		10 years
Core Deposits | Sun Bancorp, Inc.
Business Acquisition [Line Items]
Core deposit intangible	$ 11,897