Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$ 8,190	$ 1,789	$ 31,704
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	9,616	6,591	4,850
Provision for doubtful accounts	400	911	179
Stock-based compensation	26,594	18,701	8,451
Amortization of investment premiums, net of accretion of purchase discounts	1,278	1,071	0
Deferred income taxes	4,644	(2,909)	(18,281)
Excess tax benefit from employee stock incentive plans	(9,183)	(2,019)	(25)
Loss on disposal of property and equipment	0	175	35
Change in fair value of preferred stock warrants	0	0	2,842
Revaluation of contingent liability	0	0	400
Accretion of debt discount	0	0	93
Changes in operating assets and liabilities:
Accounts receivable	(15,315)	(4,253)	(21,073)
Inventories	(4,316)	2,293	(8,116)
Deferred costs	(207)	981	(3,699)
Prepaid expenses and other current assets	62	(2,459)	(1,313)
Other assets	(286)	134	(228)
Accounts payable	4,426	2,792	4,031
Accrued compensation	2,006	2,304	4,573
Accrued liabilities	(731)	2,715	364
Deferred revenue	9,548	(249)	23,305
Net cash provided by operating activities	36,726	28,568	28,092
Cash flows from investing activities
Purchase of investments	(174,710)	(83,442)	0
Proceeds from the maturity of investments	88,237	8,324	0
Proceeds from the sale of investments	3,012	13,128	0
Purchase of property and equipment	(9,479)	(7,776)	(7,531)
Increase in facility lease deposits	(96)	(300)	(591)
Cash used in acquisition	0	(7,882)	(2,000)
Increase in restricted cash	0	(5,000)	0
Net cash used in investing activities	(93,036)	(82,948)	(10,122)
Cash flows from financing activities:
Proceeds from exercise of stock options	7,632	7,236	630
Proceeds from employee stock purchase plan	4,296	3,860	0
Excess tax benefit from employee stock incentive plans	9,183	2,019	25
Initial public offering costs	0	(839)	(2,812)
Proceeds from initial public offering	0	0	97,650
Proceeds from exercise of unvested stock options, net of repurchases	0	0	2
Payments on credit facilities	0	0	(5,000)
Payments on loans payable	0	0	(8,562)
Proceeds from issuance of redeemable convertible preferred stock	0	0	25,000
Issuance costs for redeemable convertible preferred stock	0	0	(117)
Settlement of contingent consideration	0	0	(2,600)
Net cash provided by financing activities	21,111	12,276	104,216
Net increase (decrease) in cash and cash equivalents	(35,199)	(42,104)	122,186
Cash and cash equivalents at beginning of year	91,282	133,386	11,200
Cash and cash equivalents at end of year	56,083	91,282	133,386
Supplemental disclosure of cash flow information
Income taxes paid	740	915	934
Interest paid	0	0	761
Noncash investing and financing activities
Purchases of property and equipment recorded in accounts payable & accrued liabilities	1,091	1,111	928
Vesting of early exercised stock options	0	35	113
Conversion of preferred stock into common stock	0	0	77,729
Cashless exercise of preferred stock warrant	0	0	1,589
Unpaid offering costs in additional paid-in capital	$ 0	$ 0	$ 839