Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets [Abstract]
Accruals and reserves	$ 36,128	$ 31,191
Deferred revenue	41,820	25,365
Tax credits	43,657	60,331
Net operating losses	89,856	61,205
Other	8,452	8,580
Stock option compensation	54,852	38,834
Valuation allowance	(18,185)	(9,235)
Total deferred tax assets	256,580	216,271
Deferred Tax Liabilities [Abstract]
Depreciation and amortization	(40,159)	(27,648)
Acquired technology	(140,017)	(78,456)
Prepaid expenses	(17,093)	(16,839)
Total deferred tax liabilities	(197,269)	(122,943)
Total net deferred tax assets	$ 59,311	$ 93,328