Valuation and Qualifying Accounts (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for Uncollectible Trade Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		$ 8,280,000	$ 6,910,000	$ 6,728,000
Charged to Costs & Expenses		308,000	135,000	180,000
Charged to Other Accounts	[1]	11,510,000	1,242,000	5,000
Deductions	[2]	(37,000)	(7,000)	(3,000)
Balance at End of Year		20,061,000	8,280,000	6,910,000
Deferred tax valuation allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		6,518,000	4,713,000	3,128,000
Charged to Costs & Expenses		1,495,000	1,805,000	1,585,000
Balance at End of Year		$ 5,023,000	$ 6,518,000	$ 4,713,000

[1] Expected customer account adjustments charged to revenue and write-offs, net of recoveries.

[2] Represents bad debt recoveries.