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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For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

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For each income statement presented, the amount charged to expense for amortization of capitalized computer software costs.

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The gross amount of capitalized computer software costs as of the balance sheet date.

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The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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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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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.

+ References

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Property and Equipment (Details) (USD $)	12 Months Ended
Property and Equipment (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amount of property and equipment
Property and Equipment gross	$ 180,504,000	$ 141,931,000
Accumulated depreciation and amortization	67,979,000	51,221,000
Property and Equipment net	112,525,000	90,710,000
Depreciation expense	18,600,000	15,500,000	9,300,000
Land
Amount of property and equipment
Property and Equipment gross	4,653,000	5,008,000
Buildings and Leasehold improvements
Amount of property and equipment
Property and Equipment gross	21,081,000	14,640,000
Buildings and Leasehold improvements \| Minimum
Amount of property and equipment
Estimated Useful Lives	3 years
Buildings and Leasehold improvements \| Maximum
Amount of property and equipment
Estimated Useful Lives	15 years
Office equipment, furniture and fixtures
Amount of property and equipment
Property and Equipment gross	8,415,000	6,467,000
Office equipment, furniture and fixtures \| Minimum
Amount of property and equipment
Estimated Useful Lives	3 years
Office equipment, furniture and fixtures \| Maximum
Amount of property and equipment
Estimated Useful Lives	7 years
Computer equipment and software costs
Amount of property and equipment
Property and Equipment gross	80,233,000	67,498,000
Computer software costs
Amortization expense related to computer software costs	7,200,000	6,100,000	4,200,000
Computer equipment and software costs \| Minimum
Amount of property and equipment
Estimated Useful Lives	3 years
Computer equipment and software costs \| Maximum
Amount of property and equipment
Estimated Useful Lives	9 years
Machinery, equipment and vehicles
Amount of property and equipment
Property and Equipment gross	66,122,000	48,318,000
Machinery, equipment and vehicles \| Minimum
Amount of property and equipment
Estimated Useful Lives	3 years
Machinery, equipment and vehicles \| Maximum
Amount of property and equipment
Estimated Useful Lives	30 years
Computer software costs
Computer software costs
Computer software costs	60,465,000	50,592,000
Accumulated amortization	27,710,000	20,481,000
Computer software costs, net	32,755,000	30,111,000
Software development in progress
Computer software costs
Computer software costs	3,000,000	7,700,000
Capital leases
Amount of property and equipment
Property and Equipment gross	4,489,000	4,236,000
Accumulated depreciation and amortization	816,000	713,000
Property and Equipment net	$ 3,673,000	$ 3,523,000