Business Acquisitions - Additional Information (Detail) - USD ($)	Nov. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 152,459,000	$ 152,459,000	$ 152,459,000
Goodwill, expected to be deductible for income tax purposes		$ 6,000,000	$ 6,000,000
NBIC Holdings, Inc [Member]
Business Acquisition [Line Items]
Purchase price	$ 250,000,000
Purchase price for the acquisition in cash	$ 210,000,000
Issuance of common stock for business acquisition, number of restricted common shares	2,222,215
Purchase price for the acquisition, common stock aggregate value	$ 40,000,000
Goodwill	106,000,000
Goodwill, expected to be deductible for income tax purposes	$ 0