Summary of Significant Accounting Policies - Allowance for Doubtful Accounts and Other Accounts Receivable Allowances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance For Doubtful Accounts Receivable Rollforward
Allowance, balance at the beginning	$ 9,654	$ 10,116	$ 9,755
Provision charged to income	29	764	45
Accounts written off, net of recoveries	(358)	(1,226)	316
Allowance, balance at ending	$ 9,325	$ 9,654	$ 10,116