Risk Management and Derivatives (Details 1) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative financial instruments on consolidated statements of operations
Gain (loss) on foreign investments	$ (400,000)	$ (100,000)	$ (500,000)	$ (100,000)
Interest Expense | Cash flow interest rate swap | Designated as Hedging Instrument [Member]
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)	844,000	(85,000)	882,000	(124,000)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)	79,000	(68,000)	151,000	(240,000)
Other Expense | Foreign exchange contracts | Designated as Hedging Instrument [Member]
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)	344,000	0	344,000	0
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)	0		0
Other Expense | Foreign exchange contracts | Not Designated as Hedging Instrument [Member]
Derivative financial instruments on consolidated statements of operations
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (414,000)	$ 10,191,000	$ 9,742,000	$ 1,332,000