Intangible Assets - Summary of Goodwill by Business Segment (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Goodwill [Line Items]
Balance at beginning and end of period	$ 79,749
Balance at beginning and end of period	79,749
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at beginning and end of period	13,767
Community Banks [Member]
Goodwill [Line Items]
Balance at beginning and end of period	59,894
Other Financial Services [Member]
Goodwill [Line Items]
Balance at beginning and end of period	5,464
Executive, Operations & Support [Member]
Goodwill [Line Items]
Balance at beginning and end of period	$ 624