Intangible Assets and Goodwill - Summary of Goodwill by Business Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Balance at beginning of period	$ 79,749	$ 54,042
Acquisitions	68,855	25,707
Balance at end of period	148,604	79,749
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	13,767	8,078
Acquisitions		5,689
Balance at end of period	13,767	13,767
Community Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	59,894	39,876
Acquisitions		20,018
Balance at end of period	59,894	59,894
Pegasus Bank [Member]
Goodwill [Line Items]
Acquisitions	68,855
Balance at end of period	68,855
Other Financial Services [Member]
Goodwill [Line Items]
Balance at beginning of period	5,464	5,464
Balance at end of period	5,464	5,464
Executive, Operations & Support [Member]
Goodwill [Line Items]
Balance at beginning of period	624	624
Balance at end of period	$ 624	$ 624