The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Balance Sheet Components (Property and Equipment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Property and Equipment [Abstract]
Property and equipment	$ 237,429		$ 222,992
Less: Accumulated depreciation and amortization	(136,660)		(130,325)
Net property and equipment	100,769		92,667
Depreciation and amortization expense	9,227	6,011
Computer and Other Equipment [Member]
Property and Equipment [Abstract]
Property and equipment	138,396		135,181
Software [Member]
Property and Equipment [Abstract]
Property and equipment	17,910		17,342
Leasehold Improvements [Member]
Property and Equipment [Abstract]
Property and equipment	14,800		11,009
Building Construction-in-Progress [Member]
Property and Equipment [Abstract]
Property and equipment	9,088		6,372
Furniture and Fixtures [Member]
Property and Equipment [Abstract]
Property and equipment	4,511		4,075
Software And Website Development Costs [Member]
Property and Equipment [Abstract]
Property and equipment	$ 52,724		$ 49,013