Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 4,474	$ 1,579
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	8,826	7,050
Bad debt expense	346	211
Loss on disposal of property and equipment	1	12
Stock-based compensation	7,100	3,808
Amortization of premiums and accretion of discounts on investments	427	188
Excess tax benefits from stock-based compensation	(131)	(59)
Changes in operating assets and liabilities:
Accounts receivable	(2,042)	(688)
Prepaid expenses and other assets	(1,238)	229
Accounts payable	(48)	(939)
Accrued liabilities	364	(549)
Deferred revenues	6,907	4,732
Other noncurrent liabilities	99	(383)
Net cash provided by operating activities	25,085	15,191
Cash flows from investing activities:
Purchases of investments	(117,279)	(113,689)
Sales and maturities of investments	144,218	113,524
Purchases of property and equipment	(10,252)	(10,364)
Release of restricted cash	0	114
Net cash provided by (used in) investing activities	16,687	(10,415)
Cash flows from financing activities:
Proceeds from exercise of stock options	5,046	3,374
Excess tax benefits from stock-based compensation	131	59
Principal payments under capital lease obligations	(805)	(920)
Net cash provided by financing activities	4,372	2,513
Effect of exchange rate changes on cash and cash equivalents	(228)	(56)
Net increase in cash and cash equivalents	45,916	7,233
Cash and cash equivalents at beginning of period	42,369	34,885
Cash and cash equivalents at end of period	88,285	42,118
Non-cash investing and financing activities:
Purchases of property and equipment recorded in accrued liabilities	0	731
Vesting of early exercised common stock options	$ 41	$ 204