Selected Quarterly Financial Data - Summary of Quarterly Financial Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2015		Jan. 31, 2014		Jan. 31, 2013
Revenues:
Subscription services	$ 66,535	$ 61,435	$ 56,572	$ 48,521	$ 45,686	$ 38,935	$ 34,063	$ 27,937	$ 233,063		$ 146,621		$ 73,280
Professional services and other	20,477	22,390	19,092	18,200	17,117	16,044	15,518	14,851	80,159		63,530		56,268
Total revenues	87,012	83,825	75,664	66,721	62,803	54,979	49,581	42,788	313,222		210,151		129,548
Cost of revenues:
Cost of subscription services	15,210	14,409	13,346	12,040	11,790	9,511	7,948	6,950	55,005	[1]	36,199	[1]	18,852	[1]
Cost of professional services and other	15,946	16,007	14,790	13,910	12,568	11,881	11,195	10,759	60,653	[1]	46,403	[1]	38,164	[1]
Total cost of revenues	31,156	30,416	28,136	25,950	24,358	21,392	19,143	17,709	115,658	[1]	82,602	[1]	57,016	[1]
Gross profit	55,856	53,409	47,528	40,771	38,445	33,587	30,438	25,079	197,564		127,549		72,532
Operating expenses:
Research and development	11,742	10,635	9,787	8,992	7,858	6,585	6,357	5,527	41,156	[1]	26,327	[1]	14,638	[1]
Sales and marketing	15,328	14,251	13,810	12,814	12,768	11,467	9,610	7,662	56,203	[1]	41,507	[1]	19,490	[1]
General and administrative	8,103	8,582	7,146	6,408	6,511	5,550	4,633	3,717	30,239	[1]	20,411	[1]	8,371	[1]
Total operating expenses	35,173	33,468	30,743	28,214	27,137	23,602	20,600	16,906	127,598	[1]	88,245	[1]	42,499	[1]
Operating income	20,683	19,941	16,785	12,557	11,308	9,985	9,838	8,173	69,966		39,304		30,033
Other income (expense), net	(1,660)	(989)	(101)	(30)	(365)	125	(65)	(499)	(2,780)		(804)		(940)
Income before income taxes	19,023	18,952	16,684	12,527	10,943	10,110	9,773	7,674	67,186		38,500		29,093
Provision for income taxes	5,697	8,694	7,106	5,306	4,696	3,585	3,775	2,829	26,803		14,885		10,310
Net income	13,326	10,258	9,578	7,221	6,247	6,525	5,998	4,845	40,383		23,615		18,783
Net income attributable to Class A and Class B common stockholders, basic and diluted	$ 13,288	$ 10,198	$ 9,490	$ 7,128	$ 6,145	$ 2,339	$ 1,275	$ 926	$ 40,138		$ 10,405		$ 3,480
Net income per share attributable to Class A and Class B common stockholders:
Basic	$ 0.10	$ 0.08	$ 0.07	$ 0.06	$ 0.05	$ 0.07	$ 0.05	$ 0.04	$ 0.31		$ 0.20		$ 0.17
Diluted	$ 0.09	$ 0.07	$ 0.07	$ 0.05	$ 0.04	$ 0.05	$ 0.03	$ 0.03	$ 0.28		$ 0.15		$ 0.11
Weighted-average shares used to compute net income per share attributable to Class A and Class B common stockholders:
Basic	130,345	129,212	127,314	123,902	122,578	35,802	24,418	21,610	127,713		51,725		20,887
Diluted	144,737	144,289	143,353	142,849	143,221	131,963	37,038	32,988	144,204		68,024		30,599

[1] (1) Includes stock-based compensation as follows:   Cost of revenues: Cost of subscription services$273 $118 $3 Cost of professional services and other 2,272 902 120 Research and development 3,844 1,700 238 Sales and marketing 3,221 1,788 140 General and administrative 4,715 2,442 214 Total stock-based compensation$14,325 $6,950 $715