Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Cash Flows [Abstract]
Net loss	$ (6,795)	$ (11,667)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,079	5,902
Deferred income taxes	107	125
Bad debt expense and other reserves	412	384
Stock-based compensation	5,907	5,892
Non-cash interest expense on lease financing obligation	172	158
Write-off and loss on disposal of fixed assets	35	258
Changes in operating assets and liabilities:
Accounts receivable	593	3,471
Prepaid expenses	(1,156)	920
Other current assets	(6,702)	173
Other assets	(126)	(2)
Accounts payable	(3,313)	(6,058)
Accrued employee expenses	7,973	(708)
Accrued expenses and other liabilities	2,105	708
Other liabilities	(274)	(46)
Net cash used in operating activities	5,017	(490)
Cash flows from investing activities
Purchase of property and equipment	(5,473)	(6,308)
Net cash used in investing activities	(5,473)	(6,308)
Cash flows from financing activities
Repurchase of common stock option awards	0	(100)
Proceeds from exercise of common stock options	7,730	659
Taxes paid related to net share settlement of equity awards	(477)	(161)
Net cash provided by financing activities	7,253	398
Net decrease in cash and cash equivalents	6,797	(6,400)
Cash and cash equivalents at beginning of period	107,721	112,371
Cash and cash equivalents at end of period	114,518	105,971
Supplemental disclosures of non-cash activities
Stock-based compensation capitalized for software development	218	245
Capitalized assets included in accounts payable, accrued employee expenses and other accrued expenses	1,488	216
Proceeds receivable from exercise of stock options included in other current assets	615	0
Taxes payable related to net share settlement of equity awards included in accrued employee expenses	$ 212	$ 0