Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 2,280	$ 1,954	$ 847
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	7,341	5,373	4,569
Bad debt expense	218	193	117
Loss on disposal of property and equipment	10	1	13
Stock-based compensation	3,452	2,147	1,870
Non-cash interest expense	24	36	12
Amortization of premiums on short-term investments	7	0	0
Changes in operating assets and liabilities:
Accounts receivable	(4,014)	(6,651)	(1,166)
Prepaid expenses and other assets	91	(3,835)	(112)
Accounts payable	(242)	1,248	(82)
Accrued liabilities	(1,163)	2,817	(182)
Deferred revenues	13,683	11,885	4,415
Income taxes payable	181	333	(488)
Other noncurrent liabilities	84	1,689	83
Net cash provided by operating activities	21,952	17,190	9,896
Cash flows from investing activities:
Purchases of short-term investments	(83,547)	0	0
Purchases of property and equipment	(11,188)	(7,499)	(1,510)
Purchases of intangible assets	(49)	0	0
Acquisition of business, net	0	0	(2,751)
Net cash used in investing activities	(94,784)	(7,499)	(4,261)
Cash flows from financing activities:
Proceeds from initial public offering, net of offering costs	84,534	0	0
Proceeds from exercise of stock options	1,685	948	522
Proceeds from early exercise of stock options	384	390	80
Proceeds from issuance of Series C Preferred Stock	0	128	0
Principal payments under capital lease obligations	(2,401)	(1,476)	(1,149)
Non-contingent payment related to acquisition	(1,000)	0	0
Net cash provided by (used in) financing activities	83,202	(10)	(547)
Effect of exchange rate changes on cash and cash equivalents	(33)	(143)	(27)
Net increase in cash and cash equivalents	10,337	9,538	5,061
Cash and cash equivalents at beginning of period	24,548	15,010	9,949
Cash and cash equivalents at end of period	34,885	24,548	15,010
Supplemental disclosures of cash flow information
Cash paid for interest expense	162	128	163
Cash paid for income taxes, net of refunds	299	108	303
Non-cash investing and financing activities
Purchase of property and equipment under capital lease	0	3,100	2,467
Vesting of early exercised common stock options	155	52	32
Conversion of convertible preferred stock to common stock	63,873	0	0
Issuance of common stock for acquisition of business	0	0	77
Issuance of common stock for acquisition of license	$ 51	$ 0	$ 0