The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jan. 29, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 75,717,000		$ 75,717,000			$ 0
Amortization expense	1,300,000	$ 800,000	3,900,000	$ 2,400,000
Impairment of intangible assets	$ 0	$ 0	$ 0	$ 0
Customer Relationships \| Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortized period			10 years
Customer Relationships \| Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortized period			14 years
Radius Bancorp, Inc. Merger
Finite-Lived Intangible Assets [Line Items]
Goodwill					$ 75,717,000