CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Cash flows from operating activities
Net loss	$ (36,681)	$ (10,992)	$ (3,806)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization	4,674	2,120	958
Change in fair value of preferred stock warrants	14,087	2,034	366
Stock-based compensation expense	19,480	3,760	1,585
Excess tax benefits from employee stock plans	(462)
Changes in operating assets and liabilities
Accounts receivable, net	(29,453)	(20,347)	(7,558)
Prepaid expenses, other current and non-current assets	(2,658)	(3,511)	(891)
Accounts payable	187	55	535
Accrued compensation	11,981	8,697	5,126
Accrued expenses and other liabilities	3,446	2,448	1,074
Deferred revenue	62,047	30,358	10,990
Net cash provided by operating activities	46,648	14,622	8,379
Cash flows from investing activities
Change in restricted cash	514	128	161
Purchases of property and equipment	(9,077)	(8,180)	(1,471)
Net cash used in investing activities	(8,563)	(8,052)	(1,310)
Cash flows from financing activities
Payments of financing obligation under sale leaseback		(173)	(175)
Repayments of term debt	(2,289)	(711)
Proceeds from term debt		3,000
Proceeds from initial public offering, net of offering costs	225,225
Proceeds from exercise of warrant	631	50
Proceeds from early exercise of employee stock options		1,139	108
Proceeds from exercise of stock options	6,896	1,987	930
Excess tax benefits from employee stock plans	462
Proceeds from employee stock purchase plan	5,310
Net cash provided by financing activities	236,235	5,292	863
Effect of exchange rate changes on cash and cash equivalents	20
Net increase in cash and cash equivalents	274,340	11,862	7,932
Cash and cash equivalents
Beginning of period	31,599	19,737	11,805
End of period	305,939	31,599	19,737
Supplemental disclosures
Cash paid for interest	40	111	16
Cash paid for income taxes	118
Non-cash investing and financing activities
Accrued purchases of property and equipment	467	584	143
Conversion of preferred stock to common stock upon initial public offering	40,913
Vesting of early exercised options	845	128	32
Conversion of warrant liability to Series A convertible preferred stock upon exercise of warrant		914
Deferred offering costs not yet paid		$ 1,339