Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (26,164)	$ (36,354)	$ (25,063)
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of deferred implementation, solution and other costs	7,455	6,775	5,007
Depreciation and amortization	14,946	12,199	6,847
Amortization of debt issuance costs	28	96	96
Amortization of premiums on investments	319	425	319
Stock-based compensation expenses	20,939	12,640	7,362
Deferred income taxes	(350)	281	85
Allowance for sales credits	(3)	17	38
Loss on disposal of long-lived assets	33	184	0
Impairment of intangible assets	0	20	0
Unoccupied lease charges	0	33	0
Changes in operating assets and liabilities:
Accounts receivable, net	(961)	(3,247)	(3,322)
Prepaid expenses and other current assets	240	(237)	(150)
Deferred solution and other costs	(5,353)	(7,100)	(4,659)
Deferred implementation costs	(5,179)	(6,076)	(4,118)
Other long-term assets	(236)	47	(1)
Accounts payable	3,367	426	1,343
Accrued liabilities	(4,369)	10,641	4,056
Deferred revenue	4,837	9,593	14,021
Deferred rent and other long-term liabilities	(77)	3,031	3,538
Net cash provided by operating activities	9,472	3,394	5,399
Cash flows from investing activities:
Purchases of investments	(27,749)	(40,160)	(43,928)
Maturities of investments	27,907	41,105	20,908
Purchases of property and equipment	(12,315)	(14,349)	(7,128)
Business combinations and asset acquisitions, net of cash acquired	(3,816)	(95)	(27,469)
Purchase of intangible assets	0	(323)	0
Capitalized software development costs	(970)	(2,692)	(313)
Increase in restricted cash	(1,000)	0	(486)
Net cash used in investing activities	(17,943)	(16,514)	(58,416)
Cash flows from financing activities:
Payments on financing obligations	0	(4,890)	(4,241)
Payments on capital lease obligations	0	(161)	(418)
Proceeds from the issuance of common stock, net of issuance costs	0	(8)	52,575
Proceeds from exercise of stock options to purchase common stock	11,559	6,003	4,171
Net cash provided by financing activities	11,559	944	52,087
Net increase (decrease) in cash and cash equivalents	3,088	(12,176)	(930)
Cash and cash equivalents, beginning of period	54,873	67,049	67,979
Cash and cash equivalents, end of period	57,961	54,873	67,049
Supplemental disclosures of cash flow information:
Cash paid for taxes	128	120	60
Cash paid for interest	68	217	212
Supplemental disclosure of non-cash investing and financing activities:
Acquisition consideration payable to seller - working capital adjustment	0	0	95
Acquisition consideration payable to seller - hold back	150	0	2,500
Shares acquired to settle the exercise of stock options	438	376	21
Data center assets acquired under deferred payment arrangements or financing arrangements	$ 4,102	$ 0	$ 4,087