Certain Balance Sheet Accounts (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of Property and Equipment
Total property and equipment	$ 74,057	$ 74,495
Less accumulated depreciation and amortization	27,757	24,047
Property and equipment, net	46,300	50,448
Computers and equipment [Member]
Summary of Property and Equipment
Total property and equipment	17,614	19,965
Computer software [Member]
Summary of Property and Equipment
Total property and equipment	22,242	19,685
Furniture and fixtures [Member]
Summary of Property and Equipment
Total property and equipment	8,561	8,566
Leasehold improvements [Member]
Summary of Property and Equipment
Total property and equipment	$ 25,640	$ 26,279

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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