SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 0	$ 0	$ 15
Charged to Costs and Expenses		0	2
Deductions/ Write-offs (Recoveries)		0	17
Balance at End of Period	$ 0	$ 0	$ 0