Derivative Financial Instruments (Details)	3 Months Ended										3 Months Ended
	Mar. 31, 2012 USD ($)	Mar. 31, 2012 AUD	Mar. 31, 2012 CHF	Mar. 31, 2012 GBP (£)	Mar. 31, 2012 JPY (¥)	Mar. 31, 2012 NOK	Mar. 31, 2012 NZD	Mar. 31, 2012 SEK	Mar. 31, 2012 SGD	Dec. 31, 2011 USD ($)	Mar. 31, 2012 Interest Rate Swap [Member] Cash Flow Hedging [Member] Interest Expense [Member] USD ($)	Mar. 31, 2011 Interest Rate Swap [Member] Cash Flow Hedging [Member] Interest Expense [Member] USD ($)	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] Other Expense [Member] USD ($)	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] Other Expense [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Accrued Expenses And Other Current Liabilities [Member] Interest Rate Swap [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Accrued Expenses And Other Current Liabilities [Member] Interest Rate Swap [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] Interest Rate Swap [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] Interest Rate Swap [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Accrued Expenses And Other Current Liabilities [Member] Foreign Exchange Forward [Member] USD ($)	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Accrued Expenses And Other Current Liabilities [Member] Foreign Exchange Forward [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Prepaid Expenses and Other Current Assets [Member] Foreign Exchange Forward [Member] USD ($)
Interest Rate Risk [Abstract]
Term of interest rate swap (in years)	4 Y	4 Y	4 Y	4 Y	4 Y	4 Y	4 Y	4 Y	4 Y
LIBOR-based interest rate	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%	LIBOR-based interest rate to 1.25%
Senior credit facility balance covered under interest rate swap contracts	$ 250,000,000
Foreign currency denomination notional amount [Abstract]
Japanese Yen					45,537
Swedish Krona								1,725
Norwegian Krone						509
Australian Dollar		302
New Zealand Dollar							219
Singapore Dollar									100
United States Dollar	896
Swiss Franc			87
Great Britain Pound				14
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	3,065,000									3,551,000					3,065,000	2,616,000	1,890,000	1,471,000	1,175,000	1,145,000	0	935,000
Fair value of derivative asset										0													214,000
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in AOCI on derivative (effective portion)											(449,000)	848,000	0	0
Amount of gain/(loss) reclassified from AOCI into income (effective portion)											(790,000)	(864,000)	0	0
Amount of gain/(loss) recognized in income on derivative (ineffective portion)											$ 0	$ 0	$ 608,000	$ 1,249,000