Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net loss	$ (40,426)	$ (31,390)	$ (63,900)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	9,700	7,037	3,714
Accretion of debt discount and amortization of debt issuance costs	4,273	143	579
Purchased investment premium, net of amortization	(2,031)	0	0
Change in fair value of preferred stock warrant liabilities	0	0	42,559
Unrealized foreign exchange loss (gain)	242	(182)	460
Charges related to the issuance of common stock warrants to a distributor	0	0	2,500
Stock-based compensation expense	20,840	12,207	4,502
Withdrawn secondary offering expense	0	0	555
Non-cash charitable contribution of common stock	0	0	193
Deferred income taxes	(865)	(965)	0
Changes in operating assets and liabilities, net of effects from acquisition:
Accounts receivable	(19,046)	(12,254)	(13,308)
Deferred commissions	(7,085)	(5,691)	(1,274)
Prepaid expenses and other assets	(6,057)	(4,188)	(1,804)
Accounts payable	5,082	190	915
Accrued expenses	6,828	6,325	3,314
Deferred revenue	45,230	35,327	22,161
Other liabilities	746	3,735	666
Net cash provided by operating activities	17,431	10,294	1,832
Cash flows from investing activities:
Purchases of investments	203,959	0	34,079
Maturities of investments	6,182	0	34,000
Purchases of property and equipment	(8,762)	(2,123)	(784)
Capitalized software costs	(6,906)	(5,030)	(3,022)
Cash paid for acquisition, net of cash acquired	0	(12,428)	0
Net cash used in investing activities	(213,445)	(19,581)	(3,885)
Cash flows from financing activities:
Proceeds from issuance of convertible notes, net	245,664	0	0
Payments for convertible note hedges	(49,537)	0	0
Proceeds from the issuance of warrants	23,225	0	0
Proceeds from initial public offering, net of underwriting discounts and commissions	0	0	90,539
Payments of initial public offering costs	0	0	(3,436)
Proceeds from issuance of preferred stock upon warrant exercises	0	0	3,163
Payments of withdrawn secondary offering costs	0	0	(555)
Proceeds from the issuance of debt	1,914	1,043	669
Repayment of debt	(4,038)	(1,510)	(9,207)
Principal payments under capital lease obligations	(1,747)	(1,919)	(1,977)
Proceeds from stock option and warrant exercises	13,447	2,698	1,491
Payment of withholding tax on net exercise of stock-based awards	0	0	(48)
Net cash provided by financing activities	228,928	312	80,639
Effect of exchange rate changes on cash and cash equivalents	227	8	(244)
Net increase (decrease) in cash and cash equivalents	33,141	(8,967)	78,342
Cash and cash equivalents at beginning of period	76,442	85,409	7,067
Cash and cash equivalents at end of period	109,583	76,442	85,409
Supplemental cash flow information:
Cash paid for interest	2,294	341	543
Cash paid for income taxes	485	103	104
Non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock	0	0	132,775
Assets acquired under capital leases and other financing arrangements	88	3,722	1,131
Common stock issued for business acquisition	0	335	0
Capitalized assets financed by accounts payable and accrued expenses	1,175	693	25
Capitalized stock-based compensation	$ 941	$ 556	$ 234