Fair Value Measurements and Derivative Instruments (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Derivative [Line Items]
Other current assets and prepayments: Foreign exchange contracts	$ 408,000				$ 546,000
Accounts payable and accrued liabilities: Foreign exchange contracts	(284,000)				(526,000)
Other current assets and prepayments: Foreign exchange contracts	513,000				812,000
Accounts payable and accrued liabilities: Foreign exchange contracts	(1,656,000)				(2,483,000)
Total derivative assets	921,000				1,358,000
Total derivative liabilities	(1,940,000)				(3,009,000)
Total net derivative liabilities	(1,019,000)				(1,651,000)
Derivative Gain Recognized in Earnings	0		1,993,000
Hedged Item Expense Recognized in Earnings	0		(5,484,000)
Total notional amount of outstanding contracts in cash flow hedging relationships	28,000,000				26,000,000
Derivative Gain (Loss) Recognized in AOCI (Effective Portion) - Foreign exchange contracts	(69,000)		630,000
Derivative Gain (Loss) Recognized in AOCI (Effective Portion) - Revenue	937,497,000		909,363,000
Derivative Gain (Loss) Recognized in Earnings - Foreign exchange contracts - Selling, general and administrative expenses	(682,000)		(4,351,000)
Amount of collateral that would be required to be posted if our long-term senior unsecured debt ratings was to have fallen below BB-/Ba3	1,000,000
Gain (Loss) Reclassified from AOCI to Earnings (Effective Portion)
Derivative [Line Items]
Derivative Gain (Loss) Recognized in AOCI (Effective Portion) - Revenue	(234,000)	[1]	(382,000)	[1]
Derivative Gain (Loss) Recognized in AOCI (Effective Portion) - Cost of sales	199,000	[1]	126,000	[1]
Derivative Gain (Loss) Recognized in AOCI (Effective Portion)	(35,000)		(256,000)
Interest Rate Swap
Derivative [Line Items]
Total notional amount of outstanding contracts in cash flow hedging relationships			$ 450,000,000

[1] Amounts in parentheses indicate debits (reductions) to income.