Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income (loss)	$ 5,175	$ (4,381)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Stock-based compensation	2,837	1,712
Depreciation and amortization	1,607	992
Loss on disposal of fixed assets		1
Discount/premium on investments	691	399
Amortization of warrant issuance costs	82	45
Changes in operating assets and liabilities:
Disbursement prefunding	(23,243)	884
Customer funds receivable	(14,159)	(12,997)
Prepaid expenses and other current assets	636	(2,786)
Other assets	(619)	(212)
Customer liabilities	4,185	12,409
Transaction loss reserves	(101)	176
Accounts payable and accrued expenses	1,591	1,193
Other non-current liabilities	14
Net cash used in operating activities	(21,304)	(2,565)
Cash flows from investing activities:
Purchase of property, equipment, software and intangible assets	(2,531)	(2,393)
Purchase of marketable securities	(106,806)	(22,638)
Proceeds from sales and maturities of marketable securities	36,538	18,822
Change in restricted cash	(1,075)	(7,605)
Net cash used in investing activities	(73,874)	(13,814)
Cash flows from financing activities:
Net proceeds from issuance of preferred stock		(6)
Proceeds from exercise of common stock options	3,368	92
Net borrowings (repayments) under line of credit	(40,000)	14,000
Proceeds from initial public offering, net of costs	88,422
Proceeds from follow-on offering, net of costs	104,799
Net cash provided by financing activities	156,589	14,086
Net increase (decrease) in cash and cash equivalents	61,411	(2,293)
Cash and cash equivalents, beginning of period	45,077	48,248
Cash and cash equivalents, end of period	106,488	45,955
Supplemental disclosures of cash flow information:
Cash paid for taxes	34	2
Cash paid for interest	2,114	692
Purchases of property and equipment in accounts payable and accrued expenses	580	217
Deferred offering costs not yet paid	$ 535	$ 526