Certain Balance Sheet Components Depreciation Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Depreciation expense [Line Items]
Depreciation expense	$ 15,019	$ 16,571	$ 30,333	$ 32,505