Property and Equipment - Balances by Major Asset Class (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Property and equipment
Property and equipment, gross	$ 115,874	$ 108,008
Less: Accumulated depreciation and amortization	45,588	40,368
Property and equipment, net	70,286	67,640
Computer equipment
Property and equipment
Property and equipment, gross	41,106	40,349
Software
Property and equipment
Property and equipment, gross	53,837	42,614
Furniture and fixtures
Property and equipment
Property and equipment, gross	8,802	8,652
Leasehold improvements
Property and equipment
Property and equipment, gross	4,895	4,392
Projects in progress
Property and equipment
Property and equipment, gross	$ 7,234	$ 12,001

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
-Section 50
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(13))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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