Unaudited Condensed Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Revenue:
Interest income	$ 48,699	$ 26,348
Gain on sales of loans	6,679us-gaap_GainLossOnSalesOfLoansNet	1,343us-gaap_GainLossOnSalesOfLoansNet
Other revenue	1,080	871
Gross revenue	56,458us-gaap_Revenues	28,562us-gaap_Revenues
Cost of revenue:
Provision for loan losses	23,101us-gaap_ProvisionForLoanAndLeaseLosses	16,579us-gaap_ProvisionForLoanAndLeaseLosses
Funding costs	5,045us-gaap_InterestExpenseBorrowings	4,640us-gaap_InterestExpenseBorrowings
Total cost of revenue	28,146us-gaap_CostOfRevenue	21,219us-gaap_CostOfRevenue
Net revenue	28,312us-gaap_GrossProfit	7,343us-gaap_GrossProfit
Operating expense:
Sales and marketing	12,675us-gaap_SellingAndMarketingExpense	6,361us-gaap_SellingAndMarketingExpense
Technology and analytics	8,587ondk_TechnologyandAnalyticsExpense	2,909ondk_TechnologyandAnalyticsExpense
Processing and servicing	2,703ondk_ProcessingandServicingExpense	1,609ondk_ProcessingandServicingExpense
General and administrative	9,584us-gaap_GeneralAndAdministrativeExpense	3,392us-gaap_GeneralAndAdministrativeExpense
Total operating expense	33,549us-gaap_OperatingExpenses	14,271us-gaap_OperatingExpenses
Loss from operations	(5,237)us-gaap_OperatingIncomeLoss	(6,928)us-gaap_OperatingIncomeLoss
Other expense:
Interest expense	(106)us-gaap_InterestExpenseOther	(157)us-gaap_InterestExpenseOther
Warrant liability fair value adjustment	0us-gaap_FairValueAdjustmentOfWarrants	(6,632)us-gaap_FairValueAdjustmentOfWarrants
Total other expense	(106)us-gaap_OtherNonoperatingExpense	(6,789)us-gaap_OtherNonoperatingExpense
Loss before provision for income taxes	(5,343)	(13,717)
Provision for income taxes	0us-gaap_IncomeTaxExpenseBenefit	0us-gaap_IncomeTaxExpenseBenefit
Net loss	(5,343)us-gaap_NetIncomeLoss	(13,717)us-gaap_NetIncomeLoss
Accretion of dividends on redeemable convertible preferred stock	0	(2,605)
Net loss attributable to common stockholders	$ (5,343)	$ (16,322)
Net loss per common share:
Net loss per common share, basic and diluted	$ (0.08)us-gaap_EarningsPerShareBasicAndDiluted	$ (3.47)us-gaap_EarningsPerShareBasicAndDiluted
Weighted-average common shares outstanding:
Weighted-average common shares outstanding, basic and diluted	69,249,462	4,707,867

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