Property and Equipment (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property and Equipment
Subtotal	$ 133,096,000us-gaap_PropertyPlantAndEquipmentGross	$ 108,814,000us-gaap_PropertyPlantAndEquipmentGross
Less: Accumulated depreciation and amortization	(58,728,000)	(53,021,000)
Property and equipment, net	74,368,000us-gaap_PropertyPlantAndEquipmentNet	55,793,000us-gaap_PropertyPlantAndEquipmentNet	46,798,000us-gaap_PropertyPlantAndEquipmentNet
Capitalized interest costs related to internally developed software costs during development	600,000us-gaap_InterestCostsCapitalized	300,000us-gaap_InterestCostsCapitalized
Depreciation and amortization expense for property and equipment, including fixed assets under capital leases	10,300,000us-gaap_DepreciationAndAmortization	9,300,000us-gaap_DepreciationAndAmortization	9,000,000us-gaap_DepreciationAndAmortization
Computers, software, machinery and equipment
Property and Equipment
Subtotal	65,694,000	64,188,000
Leasehold improvements
Property and Equipment
Subtotal	7,797,000	5,390,000
Furniture and fixtures
Property and Equipment
Subtotal	6,020,000	4,900,000
Building and improvements
Property and Equipment
Subtotal	18,674,000	10,401,000
Land
Property and Equipment
Subtotal	12,007,000	12,007,000
Software development and other equipment in progress
Property and Equipment
Subtotal	$ 22,904,000	$ 11,928,000

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Amount of interest capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Allowance for Funds Used during Construction

-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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-Name Regulation S-X (SX)

-Number 210

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