Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Revenues:
Subscription services		$ 434,316	$ 316,314	$ 233,063
Professional services and other		109,727	92,907	80,159
Total revenues		544,043	409,221	313,222
Cost of revenues:
Cost of subscription services	[1]	94,386	71,180	55,005
Cost of professional services and other	[1]	79,295	71,034	60,653
Total cost of revenues	[1]	173,681	142,214	115,658
Gross profit		370,362	267,007	197,564
Operating expenses:
Research and development	[1]	96,750	65,976	41,156
Sales and marketing	[1]	116,803	80,984	56,203
General and administrative	[1]	48,841	41,458	30,239
Total operating expenses	[1]	262,394	188,418	127,598
Operating income		107,968	78,589	69,966
Other income (expense), net		1,667	28	(2,780)
Income before income taxes		109,635	78,617	67,186
Provision for income taxes		40,831	24,157	26,803
Net income		68,804	54,460	40,383
Net income attributable to Class A and Class B common stockholders, basic and diluted		$ 68,801	$ 54,413	$ 40,138
Net income per share attributable to Class A and Class B common stockholders:
Basic		$ 0.51	$ 0.41	$ 0.31
Diluted		$ 0.47	$ 0.38	$ 0.28
Weighted-average shares used to compute net income per share attributable to Class A and Class B common stockholders:
Basic		135,698	132,020	127,713
Diluted		147,578	144,977	144,204
Other comprehensive income (loss):
Net change in unrealized gains (losses) on available-for-sale investments		$ (153)	$ (181)	$ 76
Net change in cumulative foreign currency translation gain (loss)		92	327	(69)
Comprehensive income		$ 68,743	$ 54,606	$ 40,390

[1] Includes stock-based compensation as follows:   Cost of revenues: Cost of subscription services$1,109 $563 $273 Cost of professional services and other 6,002 3,858 2,272 Research and development 11,937 7,249 3,844 Sales and marketing 13,271 6,861 3,221 General and administrative 8,479 5,727 4,715 Total stock-based compensation$40,798 $24,258 $14,325