Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013
Cash flows from operating activities
Net income	$ 9,578	$ 5,998	$ 16,799	$ 10,843
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	991	511	1,921	778
Amortization of premiums on short-term investments	421	89	733	178
Stock-based compensation	3,400	1,215	6,656	1,950
Deferred income taxes		(173)		(173)
Bad debt expense	41	191	69	282
Changes in operating assets and liabilities:
Accounts receivable	(721)	453	(3,533)	(435)
Income taxes	(280)	(3,590)	(2,958)	(3,983)
Other current and long-term assets	511	(365)	(1,350)	(893)
Accounts payable	(1,210)	(401)	(298)	(2,103)
Accrued expenses and other current liabilities	(6,544)	(808)	(1,226)	4,139
Deferred revenue	10,431	3,897	17,923	9,353
Long-term liabilities	(10)	221	2	325
Net cash provided by operating activities	16,608	7,238	34,738	20,261
Cash flows from investing activities
Purchases of short-term investments	(94,776)	(1,414)	(229,892)	(2,771)
Maturities and sales of investments	40,763	1,900	44,630	2,600
Purchases of property and equipment	(24,983)	(884)	(25,282)	(1,101)
Acquisitions, net of cash acquired		(12,149)		(12,149)
Payments for capitalized internal-use software		(293)	(220)	(293)
Proceeds from note receivable–related party				253
Payments for restricted cash and deposits	4	215	1	3
Net cash used in investing activities	(78,992)	(12,625)	(210,763)	(13,458)
Cash flows from financing activities
Proceeds from early exercise of common stock options		24		67
Proceeds from exercise of common stock options	1,527	146	2,212	377
Proceeds from Employee Stock Purchase Plan	5,951		5,951
Net proceeds from (payments for) offerings	(499)	(529)	34,495	(529)
Excess tax benefits from employee stock plans	6,654		11,033
Net cash provided by (used in) financing activities	13,633	(359)	53,691	(85)
Effect of exchange rate changes on cash and cash equivalents	(21)		(57)
Net change in cash and cash equivalents	(48,772)	(5,746)	(122,391)	6,718
Cash and cash equivalents at beginning of period	188,888	44,354	262,507	31,890
Cash and cash equivalents at end of period	140,116	38,608	140,116	38,608
Supplemental disclosures of other cash flow information:
Cash paid for income taxes	706	7,041	4,624	9,986
Non-cash investing and financing activities:
Property and equipment included in accounts payable and accrued expenses	(90)	8	(21)	26
Vesting of early exercised stock options	$ 112	$ 95	$ 231	$ 248