Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Statement of Cash Flows [Abstract]
Net loss	$ (37,467)	$ (38,595)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	12,474	9,234
Deferred income taxes	415	438
Bad debt expense and other reserves	605	118
Stock-based compensation	26,151	20,978
Common stock warrant expense	(788)	8,343
Imputed interest on notes receivable	0	(3)
Interest income on notes receivable	0	(1)
Accretion of beneficial conversion feature on convertible notes payable and discount on revolving line of credit	0	236
Loss on disposal of fixed assets	177	243
Changes in operating assets and liabilities:
Accounts receivable	(9,249)	(10,407)
Prepaid expenses	117	(2,695)
Other current assets	1,097	(601)
Other assets	(507)	(30)
Accounts payable	7,337	3,332
Accrued employee expenses	(8,387)	(479)
Accrued expenses and other liabilities	(1,694)	5,128
Other liabilities	7	(143)
Net cash used in operating activities	(9,712)	(4,904)
Cash flows from investing activities
Change in restricted cash	0	2,000
Purchase of property and equipment	(19,626)	(12,324)
Purchase of intangible assets	0	(365)
Notes receivable from related parties	0	(60)
Repayment of notes receivable from related parties	0	3,761
Net cash used in investing activities	(19,626)	(6,988)
Cash flows from financing activities
Proceeds from initial public offering, net of underwriting discounts and offering costs	0	69,702
Proceeds from revolving line of credit	0	5,000
Repayments under credit agreement	0	(5,000)
Proceeds from exercise of common stock options	5,566	1,909
Exercise of warrants	0	9,461
Taxes paid related to net share settlement of equity awards	(683)	0
Proceeds from financing obligation drawdown	622	0
Net cash provided by financing activities	5,505	81,072
Net (decrease) increase in cash and cash equivalents	(23,833)	69,180
Cash and cash equivalents at beginning of period	147,539	43,819
Cash and cash equivalents at end of period	123,706	112,999
Cash paid during the year for:
Recognition of leased facility asset acquired and lease financing obligation	23,349	5,970
Stock-based compensation capitalized for software development	1,064	947
Capitalized assets included in accounts payable, accrued employee expenses and other accrued expenses	4,313	471
Deferred offering costs included in accounts payable and accrued expenses	$ 0	$ 58