Intangible Assets and Goodwill - Summary of Goodwill by Business Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Balance at beginning of period	$ 148,604	$ 79,749
Acquisitions	1,318	68,855
Balance at end of period	149,922	148,604
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	13,767	13,767
Balance at end of period	13,767	13,767
Community Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	59,894	59,894
Acquisitions	1,318
Balance at end of period	61,212	59,894
Pegasus Bank [Member]
Goodwill [Line Items]
Balance at beginning of period	68,855
Acquisitions		68,855
Balance at end of period	68,855	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