Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 278,000		$ 311,000		$ 387,000
Adjustments	88,000		115,000		23,000
Deductions	(141,000)		(148,000)		(99,000)
Balance at End of Period	225,000		278,000		311,000
Allowance for Obsolete or Slow-Moving Inventory
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	1,454,000		1,439,000		1,401,000
Adjustments	176,000		251,000		224,000
Deductions	(235,000)		(236,000)		(186,000)
Balance at End of Period	1,395,000		1,454,000		1,439,000
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	1,369,000		1,376,000		1,213,000
Additions					163,000
Deductions	(15,000)	[1]	(7,000)	[1]
Balance at End of Period	$ 1,354,000		$ 1,369,000		$ 1,376,000

[1] Net operating loss carryforwards used or expired.