Fair Value Measurements (Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cost method investments	$ 19,900	$ 16,600
Cost method investments, fair value of impaired investment	100	0
Cost method investment, impairment charge	3,300	8,300	$ 3,700
Impaired investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cost method investments	3,400	8,300
Convertible debt securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2014	6,073
Purchases of Level 3 securities	1,775
Proceeds received on Level 3 securities	(501)
Total net realized losses included in earnings	(838)
Transfers out of Level 3	(4,947)
Balance at December 31, 2015	$ 1,562	$ 6,073