Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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The expense recognized in the current period that allocates the cost of nonproduction tangible assets over their useful lives.

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Amount before accumulated depreciation, depletion and amortization of 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, and furniture and fixtures.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Composition of Certain Financial Statement Captions (Property And Equipment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Property and Equipment [Line Items]
Property and Equipment, gross	$ 491,882		$ 484,069
Less: Accumulated depreciation	(345,129)		(338,206)
Property and Equipment, net	146,753		145,863
Depreciation expense	7,331	$ 7,122
Buildings
Property and Equipment [Line Items]
Property and Equipment, gross	160,830		160,796
Equipment
Property and Equipment [Line Items]
Property and Equipment, gross	128,154		126,954
Land
Property and Equipment [Line Items]
Property and Equipment, gross	10,772		10,772
Purchased software
Property and Equipment [Line Items]
Property and Equipment, gross	139,794		139,245
Furniture and fixtures
Property and Equipment [Line Items]
Property and Equipment, gross	18,312		18,103
Leasehold improvements
Property and Equipment [Line Items]
Property and Equipment, gross	20,136		18,959
Construction in progress
Property and Equipment [Line Items]
Property and Equipment, gross	$ 13,884		$ 9,240