Fair Value Measurements (Fair Value Measurements) (Details) - USD ($)	1 Months Ended
	Sep. 30, 2016	Dec. 03, 2016	Mar. 07, 2016	Nov. 28, 2015	Dec. 17, 2014
FiberRio Technology Corporation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities			$ 3,887,000
Filter Resources, Inc. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		$ 0			$ 1,154,000
Contingent consideration increase (decrease)	$ 6,000
Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		3,732,000		$ 1,285,000
Foreign exchange contracts		284,000		40,000
Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts		461,000		418,000
Other Noncurrent Liabilities [Member] | FiberRio Technology Corporation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		3,732,000	$ 3,887,000
Mutual fund investments - equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		286,000		352,000
Mutual fund investments - bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		288,000		363,000
Cash and equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		18,000		14,000
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		592,000		729,000
Level 1 [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		0		0
Foreign exchange contracts		0		0
Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts		0		0
Level 1 [Member] | Mutual fund investments - equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		286,000		352,000
Level 1 [Member] | Mutual fund investments - bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		288,000		363,000
Level 1 [Member] | Cash and equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		18,000		14,000
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 2 [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		0		0
Foreign exchange contracts		284,000		40,000
Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts		461,000		418,000
Level 2 [Member] | Mutual fund investments - equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 2 [Member] | Mutual fund investments - bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 2 [Member] | Cash and equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 3 [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FibeRio contingent earn-out, included in Accrued liabilities		3,732,000		1,285,000
Foreign exchange contracts		0		0
Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts		0		0
Level 3 [Member] | Mutual fund investments - equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 3 [Member] | Mutual fund investments - bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		0		0
Level 3 [Member] | Cash and equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted trust, included in Other noncurrent assets		$ 0		$ 0