Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 1,579	$ 1,105
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	7,050	5,397
Bad debt expense	211	182
Loss on disposal of property and equipment	12	3
Stock-based compensation	3,808	2,583
Non-cash interest expense	0	24
Amortization of premiums on investments	188	0
Changes in operating assets and liabilities:
Accounts receivable	(688)	(2,884)
Prepaid expenses and other assets	229	147
Accounts payable	(939)	(542)
Accrued liabilities	(608)	(1,529)
Deferred revenues	4,732	6,415
Other noncurrent liabilities	(383)	(232)
Net cash provided by operating activities	15,191	10,669
Cash flows from investing activities:
Purchases of investments	(113,689)	0
Sales and maturities of investments	113,524	0
Purchases of property and equipment	(10,364)	(8,104)
Release of restricted cash	114	0
Net cash used in investing activities	(10,415)	(8,104)
Cash flows from financing activities:
Proceeds from exercise of stock options	3,374	1,998
Income tax benefits from exercise of stock options	59	0
Principal payments under capital lease obligations	(920)	(1,763)
Payment of consideration related to acquisition	0	(1,000)
Payment for offering costs in connection with initial public offering	0	(560)
Net cash provided by (used in) financing activities	2,513	(1,325)
Effect of exchange rate changes on cash and cash equivalents	(56)	16
Net increase in cash and cash equivalents	7,233	1,256
Cash and cash equivalents at beginning of period	34,885	24,548
Cash and cash equivalents at end of period	42,118	25,804
Non-cash investing and financing activities:
Purchases of property and equipment included in accrued liabilities	731	0
Vesting of early exercised common stock options	204	86
Deferred offerings costs not yet paid	0	1,973
Issuance of common stock for acquisition of license	$ 0	$ 51