Risk Management and Use of Derivative Financial Instruments (Details 6) In Thousands, unless otherwise specified	Dec. 31, 2014 USD ($)	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts Euro USD ($) instrument	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts Euro EUR (€)	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts GBP USD ($) instrument	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts GBP GBP (£)	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts AUD USD ($) instrument	Dec. 31, 2014 Cash Flow Hedging Foreign currency forward contracts AUD	Dec. 31, 2014 Derivatives in Net Investment Hedging Relationships Foreign currency forward contracts AUD USD ($) instrument	Dec. 31, 2014 Derivatives in Net Investment Hedging Relationships Foreign currency forward contracts AUD
Derivative Disclosure
Derivative number of instruments		68	68	16	16	20	20	5	5
Notional Amount			€ 155,978		£ 8,560		25,082		84,522
Fair value, foreign currency derivatives	$ 16,307	$ 12,573		$ 51		$ 1,117		$ 2,566