Fair Value of Assets and Liabilities - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Net change in unrealized gain on investments, net of tax	$ 147	$ 669	$ 1,081