Schedule II - Valuation Accounts (Detail) - Allowance for Credit Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 931	$ 809	$ 1,069
Additions—charged to expense	1,360	1,620	290
Deductions—bad debts written off, net of recoveries	(823)	(1,498)	(550)
Balance at end of period	$ 1,468	$ 931	$ 809