Goodwill and other intangible assets - Additional information (Detail)
12 Months Ended
Dec. 31, 2020
USD ($)
states
Dec. 31, 2019
USD ($)
states
Goodwill and Intangible Assets Disclosure [Abstract]    
Other Intangible Assets, Net $ 3,000,000 $ 3,000,000
Number of states With Licenses | states 45 45
Goodwill $ 1,243,000 $ 1,243,000
Goodwill and Intangible Asset Impairment $ 0 $ 0