Valuation And Qualifying Accounts (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	[1]	$ 61	$ 104	$ 134
Additions (recoveries) – charged to costs and expenses	[1]	153	233	114
Deductions	[1]	0	(276)	(144)
Ending Balance	[1]	214	61	104
Deferred tax asset valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	[2]	512	1,229	49,146
Additions (recoveries) – charged to costs and expenses	[2]	0	0	0
Deductions	[2]	(385)	(717)	(47,917)
Ending Balance	[2]	$ 127	$ 512	$ 1,229

[1] We record additions to the allowance for doubtful accounts based on historical collections, write-off experience, current economic trends, and changes in customer payment terms and other factors that may affect our ability to collect payments. Deductions principally reflect amounts charged off as uncollectable, less amounts recovered.

[2] Deferred tax assets are reduced by a valuation allowance when, in our opinion, it is more likely than not that the related benefit will not be realized.