Schedule II Valuation and Qualifying Accounts - Valuation And Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 5,118	$ 13,960	$ 14,850
Charged to (Reduction in) Costs and Expenses	3,610	(1,515)	3,987
Other	1,099	386	(2,155)
Deductions	(4,244)	(7,713)	(2,722)
Balance at End of Period	5,583	5,118	13,960
Deferred tax asset valuation allowances
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	12,048	10,968	13,177
Charged to (Reduction in) Costs and Expenses	9,707	1,080	(2,209)
Other	0	0	0
Deductions	0	0	0
Balance at End of Period	$ 21,755	$ 12,048	$ 10,968