Fair Value Measurements (Schedule of Activity of Major Classes of Assets Measured at Fair Value Using Level 3 Inputs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ 137,256
Redemptions and sales of securities		(137,256)
Ending balance		0
Contingent Consideration [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	(990)
Payments		550
Change in fair value estimate		440
Contingent consideration for acquisition of Verivue	(1,200)
Ending balance	$ (1,200)	$ 0