Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Deferred Tax Assets [Abstract]
Accruals and reserves	$ 31,191	$ 24,191
Deferred revenue	25,365	19,377
Tax credits	60,331	71,442
Net operating losses	61,205	40,234
Other	8,580	3,495
Stock option compensation	38,834	27,314
Valuation allowance	9,235	13,999
Total deferred tax assets	216,271	172,054
Deferred Tax Liabilities [Abstract]
Depreciation and amortization	(27,648)	(2,684)
Acquired technology	(78,456)	(26,850)
Prepaid expenses	(16,839)	(12,479)
Total deferred tax liabilities	(122,943)	(42,013)
Total net deferred tax assets	$ 93,328	$ 130,041