Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Operating activities:
Net loss	$ (31,522)	$ (29,781)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization expense	7,319	4,335
Stock-based expense	7,656	15,933
Revaluation of contingent consideration	(3,270)
Bad debt expense	631	783
Excess tax benefit related to stock-based expense	(93)	(272)
Changes in operating assets and liabilities:
Accounts receivable	(1,789)	(4,800)
Prepaid expenses and other current assets	28	(228)
Other non-current assets	(813)	(116)
Accounts payable	(14)	3,176
Accrued expenses and other current liabilities	4,561	2,534
Deferred revenue	(3,925)	1,334
Other liabilities, long-term	(537)	1,138
Net cash used in operating activities	(21,768)	(5,964)
Investing activities:
Acquisitions, net of cash acquired, and purchase of intangible asset	(205)	(30,314)
Purchases of property, equipment and capitalized internal-use software development costs	(6,251)	(5,830)
Purchases of short-term investments	(34,117)	(66,717)
Proceeds from maturities of short-term investments	39,899	21,165
Proceeds from sales of short-term investments	17,250
Net cash provided by (used in) investing activities	16,576	(81,696)
Financing activities:
Proceeds from follow-on stock offering, net of costs		51,943
Proceeds from employee stock compensation plans	7,390	6,196
Excess tax benefit related to stock-based expense	93	272
Net cash provided by financing activities	7,483	58,411
Effect of exchange rate fluctuations on cash and cash equivalents	141	(2)
Net change in cash and cash equivalents	2,432	(29,251)
Cash and cash equivalents at beginning of period	25,045	74,367
Cash and cash equivalents at end of period	27,477	45,116
Supplemental disclosure of other cash flow information:
Cash paid for income taxes	300	236
Supplemental disclosure of non-cash investing and financing activities:
Accrued stock offering costs		246
Issuance of stock for acquisition		$ 119,696