Fair Value Measurements (Assets Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs) (Details) (Convertible Debt Securities [Member], Significant Unobservable Inputs (Level 3) [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Convertible Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2012	$ 3,341
Transfers out of Level 3	(250)
Balance at March 31, 2013	$ 3,091