Property and Equipment, net - Depreciation and Amortization (Details) (USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Property and Equipment, net
Depreciation and amortization expense			$ 9,234,000	$ 8,441,000
Property and equipment
Property and Equipment, net
Depreciation and amortization expense	2,400,000	1,700,000	6,200,000	5,200,000
Internally developed software
Property and Equipment, net
Amortization	$ 1,700,000	$ 1,100,000	$ 3,900,000	$ 2,400,000

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Name:	us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration