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	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 484,069	$ 456,383
Less: Accumulated depreciation	(338,206)	(309,955)
Property and Equipment, net	145,863	146,428
Depreciation expense	28,792	27,311	$ 26,440
Buildings
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	160,796	153,961
Equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	126,954	115,546
Land
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	10,772	10,030
Purchased software
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	139,245	134,610
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	18,103	18,114
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	18,959	18,017
Construction in progress
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 9,240	$ 6,105