Impact of New Accounting Standards - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain on equity securities		$ 8,900,000	$ 1,200,000
Loss on equity securities		$ 25,751	$ 4,400,000
Accounting Standards Update 2016-01 [Member] | Accumulated Net Unrealized Investment Losses [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings	$ 4,900,000