Intangible Assets - Summary of Goodwill by Business Segment (Detail) $ in Thousands	Sep. 30, 2016 USD ($)
Goodwill [Line Items]
Balance at December 31, 2015	$ 54,042
Balance at September 30, 2016	54,042
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at December 31, 2015	8,078
Balance at September 30, 2016	8,078
Community Banks [Member]
Goodwill [Line Items]
Balance at December 31, 2015	40,050
Balance at September 30, 2016	40,050
Other Financial Services [Member]
Goodwill [Line Items]
Balance at December 31, 2015	5,464
Balance at September 30, 2016	5,464
Executive, Operations & Support [Member]
Goodwill [Line Items]
Balance at December 31, 2015	450
Balance at September 30, 2016	$ 450