Consolidated Statements of Operations and Comprehensive Income - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Interest income	$ 334,575,000	$ 264,844,000	$ 195,048,000
Gain on sales of loans	2,485,000	14,411,000	53,354,000
Other revenue	13,890,000	12,062,000	6,365,000
Gross revenue	350,950,000	291,317,000	254,767,000
Cost of revenue:
Provision for loan losses	152,926,000	149,963,000	74,863,000
Funding costs	45,435,000	32,448,000	20,244,000
Total cost of revenue	198,361,000	182,411,000	95,107,000
Net revenue	152,589,000	108,906,000	159,660,000
Operating expense:
Sales and marketing	52,786,000	67,011,000	60,575,000
Technology and analytics	53,392,000	58,899,000	42,653,000
Processing and servicing	18,076,000	19,719,000	13,053,000
General and administrative	41,916,000	48,345,000	45,304,000
Total operating expense	166,170,000	193,974,000	161,585,000
Income (loss) from operations	(13,581,000)	(85,068,000)	(1,925,000)
Other expense:
Interest expense	(764,000)	(414,000)	(306,000)
Total other expense	(764,000)	(414,000)	(306,000)
Loss before provision for income taxes	(14,345,000)	(85,482,000)	(2,231,000)
Provision for income taxes	0	0	0
Net income (loss)	(14,345,000)	(85,482,000)	(2,231,000)
Net loss attributable to noncontrolling interest	2,811,000	2,524,000	958,000
Net income (loss) attributable to On Deck Capital, Inc. common stockholders	$ (11,534,000)	$ (82,958,000)	$ (1,273,000)
Net income (loss) per share attributable to On Deck Capital, Inc. common shareholders:
Basic and diluted (in dollars per share)	$ (0.16)	$ (1.17)	$ (0.02)
Weighted-average common shares outstanding:
Basic and diluted (in shares)	72,890,313	70,934,937	69,545,238
Comprehensive loss:
Foreign currency translation adjustment	$ 594,000	$ (20,000)	$ (678,000)
Comprehensive loss	(13,751,000)	(85,502,000)	(2,909,000)
Comprehensive loss attributable to noncontrolling interests	(267,000)	13,000	306,000
Net loss attributable to noncontrolling interest	2,811,000	2,524,000	958,000
Comprehensive loss attributable to On Deck Capital, Inc. common stockholders	$ (11,207,000)	$ (82,965,000)	$ (1,645,000)