Income Taxes (Summary Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Net operating loss carryforwards	$ 56,108	$ 61,059
Deductible goodwill and intangible assets	21,044	34,586
Tax credit carryforwards	86,951	100,190
Deferred revenue, accruals and reserves	106,572	103,794
Capital loss carryforwards and book impairment of investments	1,162,320	1,161,896
Other	5,039	4,956
Total deferred tax assets	1,438,034	1,466,481
Valuation allowance	(1,162,604)	(1,162,170)
Net deferred tax assets	275,430	304,311
Property and equipment	(10,787)	(16,115)
Convertible debentures	(538,098)	(494,625)
Other	(3,378)	(4,151)
Deferred Tax Liabilities, Gross	552,263	514,891
Total deferred tax liabilities	$ 276,833	$ 210,580