Office Facilities - Summary of Office Facilities Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Cost	$ 117,359
Accumulated depreciation/ Amortization	89,027
Net book value	28,332	16,976
Furniture, fixtures and equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	70,432
Accumulated depreciation/ Amortization	61,083
Net book value	9,349	11,628
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	46,927
Accumulated depreciation/ Amortization	27,944
Net book value	$ 18,983	$ 5,348

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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