Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 8,109	$ 5,836	$ 7,570
Charged to Income	4,925	3,401	2,019
Charged to Equity	0	0	0
Acquisition of Business	0	0	0
Deductions	1,872	1,128	3,753
Balance at  End of Year	11,162	8,109	5,836
Tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	27,270	22,620	30,102
Charged to Income	5,834	13,178	456
Charged to Equity	2,736	(6,337)	0
Acquisition of Business	0	0	0
Deductions	695	2,191	7,938
Balance at  End of Year	$ 35,145	$ 27,270	$ 22,620