Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities:
Net income (loss)	$ (39,720)	$ (41,004)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, Depletion and Amortization	4,005	4,973
Amortization of Financing Costs and Discounts	3,510	3,166
Share-based compensation	12,094	11,253
Deferred Income Tax Expense (Benefit)	33	42
Provision for doubtful accounts	0	(139)
Changes in operating assets and liabilities:
Accounts and unbilled receivables	137	2,480
Prepaid expenses and other assets	(981)	(804)
Accounts payable	2,838	(1,454)
Accrued liabilities	287	640
Accrued payroll and other employee benefits	(8,601)	(2,246)
Deferred revenue	5,089	13,721
Net cash provided by (used in) operating activities	(21,309)	(9,372)
Investing activities:
Purchases of property and equipment	(695)	(5,339)
Internal-use software development costs capitalized	(1,308)	(72)
Payments to Acquire Short-term Investments	0	(88,928)
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities	9,983	49,500
Net cash provided by (used in) investing activities	7,980	(44,839)
Financing activities:
Exercise of stock options	5,276	14
Proceeds from Stock Plans	776	470
Tax withholding related to net share settlement of restricted stock units	(5,754)	(4,839)
Repayments of Notes Payable	(155)	(91)
Payments of Debt Issuance Costs	(125)	0
Proceeds from Convertible Debt	93,500	0
Net cash provided by (used in) financing activities	93,518	(4,446)
Effect of Exchange Rate on Cash and Cash Equivalents	(259)	38
Net change in cash and cash equivalents	79,930	(58,619)
Cash and cash equivalents:
Beginning of period	118,039	161,770
End of period	$ 197,969	$ 103,151