Significant Accounting Policies (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Accounting Policies [Abstract]    
Beginning Balance $ 194,951 $ 148,534
Redemptions (1,729) (4,820)
Granted 5,704 13,327
Changes in redemption value 4,290 38,850
Currency Translation Adjustments (878) (940)
Ending Balance $ 202,338 $ 194,951