Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for doubtful accounts receivable [Member]
Deducted from asset accounts:
Balance at Beginning of Period	$ 1,421		$ 1,403		$ 1,490
Charged to Costs and Expenses	664		127		560
Charged to Other Accounts-Describe	0		(12)		(305)
Deduction-Describe	507	[1]	97	[1]	342	[1]
Balance at End of Period	1,578		1,421		1,403
Inventory reserves and obsolescence [Member]
Deducted from asset accounts:
Balance at Beginning of Period	6,333		5,872		6,336
Charged to Costs and Expenses	6,067		5,250		3,935
Charged to Other Accounts-Describe	0		0		0
Deduction-Describe	4,207	[2]	4,789	[2]	4,399	[2]
Balance at End of Period	$ 8,193		$ 6,333		$ 5,872

[1] Bad debts written-off, net of recoveries

[2] Inventory write-off