Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	$ (778)	$ (1,450)
Net unrealized (loss) gain on investments, net of taxes of $6,487 at September 30, 2011 and $5,005 at December 31, 2010	471	191
Total accumulated other comprehensive income (loss)	(307)	(1,259)
Accumulated other comprehensive income loss available for sale securities adjustment tax	$ (189)	$ (14)