Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
General business credits	$ 277	$ 25,834
Impairment losses on investments	318	2,884
Realized losses on marketable investments		2,095
License fees capitalized for tax purposes	75,181	74,964
Nonqualified stock options	40,808	30,872
SERP	14,059	14,594
STAP awards	84,274	20,238
Other	28,118	31,534
Total deferred tax assets	243,035	203,015
Deferred tax liabilities:
Plant and equipment principally due to differences in depreciation	(32,725)	(31,428)
Other	(1,351)	(1,221)
Net deferred tax asset before valuation allowance	208,959	170,366
Valuation allowance	(2,507)	(5,665)
Net deferred tax assets	$ 206,452	$ 164,701