Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement of Cash Flows [Abstract]
Net loss	$ (26,362)	$ (24,955)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8,020	5,875
Deferred income taxes	251	317
Bad debt expense and other reserves	172	109
Stock-based compensation	18,620	11,540
Common stock warrant expense	(480)	4,668
Imputed interest on notes receivable	0	10
Interest income on notes receivable	0	(18)
Accretion of beneficial conversion feature on convertible notes payable and discount on revolving line of credit	0	236
Loss on disposal of fixed assets	25	211
Changes in operating assets and liabilities:
Accounts receivable	(2,051)	(6,183)
Prepaid expenses	(3,340)	(3,319)
Other current assets	351	457
Other assets	(209)	(62)
Accounts payable	(274)	491
Accrued employee expenses	(8,192)	(410)
Accrued expenses and other liabilities	1,001	4,700
Other liabilities	11	(97)
Net cash used in operating activities	(12,457)	(6,430)
Cash flows from investing activities
Purchase of property and equipment	(14,032)	(4,790)
Purchase of intangible assets	0	(350)
Payments for Advance to Affiliate	0	(60)
Repayment of notes receivable from related parties	0	3,761
Net cash used in investing activities	(14,032)	(1,439)
Cash flows from financing activities
Payments of initial public offering costs	0	69,674
Repayments under credit agreement	0	(5,000)
Proceeds from exercise of common stock options	5,206	1,760
Proceeds from Warrant Exercises	0	9,461
Taxes paid related to net share settlement of equity awards	(610)	0
Proceeds from financing obligation drawdown	345	0
Payments related to build-to-suit financing obligations	(22)	0
Net cash provided by financing activities	4,919	75,895
Net (decrease) increase in cash and cash equivalents	(21,570)	68,026
Cash and cash equivalents at beginning of period	147,539	43,819
Cash and cash equivalents at end of period	125,969	111,845
Cash paid during the year for:
Recognition of leased facility asset acquired and lease financing obligation	22,871	0
Stock-based compensation capitalized for software development	675	614
Capitalized assets included in accounts payable, accrued employee expenses and other accrued expenses	$ (257)	$ 370