Prosper Funding 10-Q 12 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Nov. 05, 2019
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	333-225797-01
Entity Registrant Name	PROSPER MARKETPLACE, INC.
Entity Central Index Key	0001416265
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	73-1733867
Entity Address, Address Line One	221 Main Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	593-5400
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		70,637,566
Prosper Funding LLC
Entity Information [Line Items]
Entity File Number	333-225797
Entity Registrant Name	PROSPER FUNDING LLC
Entity Central Index Key	0001542574
Current Fiscal Year End Date	--12-31
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-4526070
Entity Address, Address Line One	221 Main Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	593-5479
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and Cash Equivalents		$ 55,300	$ 57,945
Restricted Cash (1)	[1]	158,302	149,114
Available for Sale Investments, at Fair Value		1,500	22,173
Accounts Receivable (1)	[1]	1,670	5,119
Loans Held for Sale, at Fair Value (1)	[1]	231,644	183,788
Borrower Loans Receivable at Fair Value	[1]	540,969	263,522
Property and Equipment, Net		31,299	15,273
Prepaid and Other Assets (1)	[1]	7,048	4,643
Servicing Assets		12,936	14,687
Goodwill		36,368	36,368
Intangible Assets, Net		789	999
Total Assets		1,077,825	753,631
Liabilities, Convertible Preferred Stock and Stockholders' Deficit
Accounts Payable and Accrued Liabilities		20,305	19,967
Payable to Investors		113,507	127,538
Notes, at Fair Value		247,725	264,003
Notes Issued by Securitization Trust (1)	[1]	260,060	0
Certificates Issued by Securitization Trust, at Fair Value	[1]	37,564	0
Warehouse Lines (1)	[1]	205,818	162,488
Other Liabilities		23,565	10,629
Convertible Preferred Stock Warrant Liability		152,342	143,679
Total Liabilities		1,060,886	728,304
Commitments and Contingencies (see Note 18)
Temporary Equity, Carrying Amount, Attributable to Parent		323,793	323,793
Stockholders' Deficit
Common Stock – $0.01 par value; 625,000,000 shares authorized; 71,502,461 shares issued and 70,566,526 shares outstanding, as of June 30, 2019; 71,411,145 shares issued and 70,475,210 shares outstanding, as of December 31, 2018		230	229
Additional Paid-In Capital		149,598	145,486
Less: Treasury Stock		(23,417)	(23,417)
Retained Earnings (Accumulated Deficit)		(433,265)	(420,751)
Accumulated Other Comprehensive Loss		0	(13)
Total Stockholders' Deficit		(306,854)	(298,466)
Total Liabilities, Convertible Preferred Stock and Stockholders' Deficit		1,077,825	753,631
Primary Beneficiary
Assets
Restricted Cash (1)	[2]	28,402	0
Accounts Receivable (1)	[2]	0	3,902
Loans Held for Sale, at Fair Value (1)	[2]	231,644	183,788
Borrower Loans Receivable at Fair Value	[2]	293,252	0
Prepaid and Other Assets (1)	[2]	3,155	1,393
Total Assets	[2]	556,453	189,083
Liabilities, Convertible Preferred Stock and Stockholders' Deficit
Notes Issued by Securitization Trust (1)	[2]	260,060	0
Certificates Issued by Securitization Trust, at Fair Value	[2]	37,564	0
Warehouse Lines (1)	[2]	205,818	162,488
Total Liabilities	[2]	503,442	162,488
Prosper Funding LLC
Assets
Cash and Cash Equivalents		13,716	11,163
Restricted Cash (1)		125,442	136,018
Borrower Loans Receivable at Fair Value		247,718	263,522
Property and Equipment, Net		4,932	6,426
Servicing Assets		15,220	15,550
Other Assets		647	323
Total Assets		407,675	433,002
Liabilities, Convertible Preferred Stock and Stockholders' Deficit
Accounts Payable and Accrued Liabilities		1,508	4,690
Payable to Related Party		574	1,283
Payable to Investors		117,758	127,253
Notes, at Fair Value		247,725	264,003
Other Liabilities		4,564	4,528
Total Liabilities		372,129	401,757
Stockholders' Deficit
Member's Equity		24,904	24,904
Retained Earnings (Accumulated Deficit)		10,642	6,341
Total Stockholders' Deficit		35,546	31,245
Total Liabilities, Convertible Preferred Stock and Stockholders' Deficit		$ 407,675	$ 433,002
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.
[2]	The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 7 - Securitizations and Note 11 - Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information.

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 20, 2017
Statement of Financial Position [Abstract]
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized (in shares)	444,760,848	444,760,848	444,760,848
Convertible preferred stock, shares issued (in shares)	214,637,925	214,637,925
Convertible preferred stock, shares outstanding (in shares)	214,637,925	214,637,925
Convertible preferred stock, aggregate liquidation preference	$ 375,952	$ 375,952
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	625,000,000	625,000,000	625,000,000
Common stock, shares issued (in shares)	71,573,501	71,411,145
Common stock, shares outstanding (in shares)	70,637,566	70,475,210

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Revenues
Revenues	$ 42,816	$ 20,595	$ 106,289	$ 78,575
Gain (Loss) on Sale of Borrower Loans	2,577	3,139	8,834	10,652
Fair Value of Warrants Vested on Sale of Borrower Loans	0	(19,561)	(17,553)	(55,473)
Interest Income
Interest Income on Borrower Loans	29,113	15,088	71,084	42,005
Interest expense	(17,339)	(11,772)	(46,104)	(33,972)
Net Interest Income	11,774	3,316	24,980	8,033
Change in Fair Value of Financial Instruments, Net	(11,229)	(3,229)	(14,901)	(3,801)
Total Net Revenue	43,361	20,682	116,368	82,807
Expenses
Origination and Servicing	8,464	8,313	26,052	26,326
Sales and Marketing	20,484	23,415	58,275	63,150
General and Administrative	18,195	18,066	54,879	54,931
Restructuring Charges, Net	7	218	86	813
Change in Fair Value of Convertible Preferred Stock Warrants	(14,217)	(9,283)	(8,890)	(17,885)
Other Expenses (Income), Net	(370)	(276)	(1,607)	(776)
Total Expenses	32,563	40,453	128,795	126,559
Net Income (Loss) Before Taxes	10,798	(19,771)	(12,427)	(43,752)
Income Tax Expense	29	8	87	27
Net Income (Loss)	10,769	(19,779)	(12,514)	(43,779)
Less: Net Income Allocated to Participating Securities	(7,994)	0	0	0
Net Income (Loss) Attributable to Common Stockholders	$ 2,775	$ (19,779)	$ (12,514)	$ (43,779)
Net Income (Loss) Per Share - Basic (in shares)	$ 0.04	$ (0.28)	$ (0.18)	$ (0.62)
Net income (loss) per share - diluted (in shares)	$ 0.01	$ (0.28)	$ (0.18)	$ (0.62)
Weighted-Average Shares - Basic (in shares)	70,606,805	70,394,269	70,532,641	70,353,819
Weighted-Average Shares - Diluted (in shares)	285,810,755	70,394,269	70,532,641	70,353,819
Prosper Funding LLC
Operating Revenues
Revenues	$ 18,538	$ 17,924	$ 54,193	$ 58,946
Gain (Loss) on Sale of Borrower Loans	3,155	(16,379)	(7,725)	(44,133)
Interest Income
Interest Income on Borrower Loans	10,304	10,939	31,038	32,797
Interest expense	(9,647)	(10,209)	(29,031)	(30,597)
Net Interest Income	657	730	2,007	2,200
Change in Fair Value on Borrower Loans, Loans Held for Sale and Notes, Net	(120)	(250)	(338)	(614)
Total Net Revenue	19,075	18,404	55,862	60,532
Expenses
Administration Fee - Related Party	16,079	16,864	47,845	55,036
Servicing	1,178	1,036	3,550	4,512
General and Administrative	38	97	166	464
Total Expenses	17,295	17,997	51,561	60,012
Income Tax Expense			0	0
Net Income (Loss)	1,780	407	4,301	520
Administration Fee Revenue - Related Party | Prosper Funding LLC
Operating Revenues
Revenues	8,854	27,135	42,469	81,754
Transaction Fees, Net
Operating Revenues
Revenues	32,466	28,225	92,637	97,567
Servicing Fees, Net
Operating Revenues
Revenues	6,165	7,339	17,540	22,009
Servicing Fees, Net | Prosper Funding LLC
Operating Revenues
Revenues	6,473	7,098	19,350	21,119
Other Revenue
Operating Revenues
Revenues	1,608	1,453	4,831	3,820
Other Revenue | Prosper Funding LLC
Operating Revenues
Revenues	$ 56	$ 70	$ 99	$ 206

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Other Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Loss	$ 10,769	$ (19,779)	$ (12,514)	$ (43,779)
Other Comprehensive Income (Loss), Before Tax
Change in Net Unrealized Gain (Loss) on Available for Sale Investments, at Fair Value	(8)	23	13	35
Other Comprehensive Income (Loss), Before Tax	(8)	23	13	35
Income Tax Effect	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(8)	23	13	35
Comprehensive Income (Loss)	$ 10,761	$ (19,756)	$ (12,501)	$ (43,744)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders’ Deficit - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings (Accumulated Deficit)	Prosper Funding LLC	Prosper Funding LLCRetained Earnings (Accumulated Deficit)	Prosper Funding LLCMember's Equity
Beginning balance (in shares) at Dec. 31, 2017		214,637,925
Beginning balance at Dec. 31, 2017		$ 323,793
Ending balance (in shares) at Mar. 31, 2018		214,637,925
Ending balance at Mar. 31, 2018		$ 323,793
Beginning balance (in shares) at Dec. 31, 2017			75,468,234	(5,177,235)
Beginning balance at Dec. 31, 2017	$ (267,415)		$ 228	$ (23,417)	$ 136,653	$ (73)	$ (380,806)	$ 30,366	$ 5,462	$ 24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			43,746
Exercise of vested stock options	8				8
Restricted stock vested	5				5
Exercise of warrants (in shares)			8,200
Exercise of warrants	0
Stock-based compensation expense	2,425				2,425
Change in net unrealized loss on available for sale investments, at fair value	(16)					(16)
Net Loss	(11,401)						(11,401)	(169)	(169)
Ending balance (in shares) at Mar. 31, 2018			75,520,180	(5,177,235)
Ending balance at Mar. 31, 2018	(276,394)		$ 228	$ (23,417)	139,091	(89)	(392,207)	30,197	5,293	24,904
Beginning balance (in shares) at Dec. 31, 2017		214,637,925
Beginning balance at Dec. 31, 2017		$ 323,793
Ending balance (in shares) at Sep. 30, 2018		214,637,925
Ending balance at Sep. 30, 2018		$ 323,793
Beginning balance (in shares) at Dec. 31, 2017			75,468,234	(5,177,235)
Beginning balance at Dec. 31, 2017	(267,415)		$ 228	$ (23,417)	136,653	(73)	(380,806)	30,366	5,462	24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Loss	(43,779)							520
Ending balance (in shares) at Sep. 30, 2018			75,652,445	(5,177,235)
Ending balance at Sep. 30, 2018	(304,415)		$ 229	$ (23,417)	143,397	(39)	(424,585)	30,886	5,982	24,904
Beginning balance (in shares) at Mar. 31, 2018		214,637,925
Beginning balance at Mar. 31, 2018		$ 323,793
Ending balance (in shares) at Jun. 30, 2018		214,637,925
Ending balance at Jun. 30, 2018		$ 323,793
Beginning balance (in shares) at Mar. 31, 2018			75,520,180	(5,177,235)
Beginning balance at Mar. 31, 2018	(276,394)		$ 228	$ (23,417)	139,091	(89)	(392,207)	30,197	5,293	24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			39,046
Exercise of vested stock options	8				8
Restricted stock vested	6				6
Stock-based compensation expense	2,358				2,358
Change in net unrealized loss on available for sale investments, at fair value	27					27
Net Loss	(12,599)						(12,599)	282	282
Ending balance (in shares) at Jun. 30, 2018			75,559,226	(5,177,235)
Ending balance at Jun. 30, 2018	(286,594)		$ 228	$ (23,417)	141,463	(62)	(404,806)	30,479	5,575	24,904
Ending balance (in shares) at Sep. 30, 2018		214,637,925
Ending balance at Sep. 30, 2018		$ 323,793
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			93,219
Exercise of vested stock options	13		$ 1		12
Restricted stock vested	2				2
Stock-based compensation expense	1,920				1,920
Change in net unrealized loss on available for sale investments, at fair value	23					23
Net Loss	(19,779)						(19,779)	407	407
Ending balance (in shares) at Sep. 30, 2018			75,652,445	(5,177,235)
Ending balance at Sep. 30, 2018	$ (304,415)		$ 229	$ (23,417)	143,397	(39)	(424,585)	30,886	5,982	24,904
Beginning balance (in shares) at Dec. 31, 2018	214,637,925	214,637,925
Beginning balance at Dec. 31, 2018	$ 323,793	$ 323,793
Ending balance (in shares) at Mar. 31, 2019		214,637,925
Ending balance at Mar. 31, 2019		$ 323,793
Beginning balance (in shares) at Dec. 31, 2018			75,652,445	(5,177,235)
Beginning balance at Dec. 31, 2018	(298,466)		$ 229	$ (23,417)	145,486	(13)	(420,751)	31,245	6,341	24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			16,085
Exercise of vested stock options	4				4
Stock-based compensation expense	1,714				1,714
Change in net unrealized loss on available for sale investments, at fair value	10					10
Net Loss	(22,714)						(22,714)	1,291	1,291
Ending balance (in shares) at Mar. 31, 2019			75,668,530	(5,177,235)
Ending balance at Mar. 31, 2019	$ (319,452)		$ 229	$ (23,417)	147,204	(3)	(443,465)	32,536	7,632	24,904
Beginning balance (in shares) at Dec. 31, 2018	214,637,925	214,637,925
Beginning balance at Dec. 31, 2018	$ 323,793	$ 323,793
Ending balance (in shares) at Sep. 30, 2019	214,637,925	214,637,925
Ending balance at Sep. 30, 2019	$ 323,793	$ 323,793
Beginning balance (in shares) at Dec. 31, 2018			75,652,445	(5,177,235)
Beginning balance at Dec. 31, 2018	(298,466)		$ 229	$ (23,417)	145,486	(13)	(420,751)	31,245	6,341	24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Loss	(12,514)							4,301
Ending balance (in shares) at Sep. 30, 2019			75,814,801	(5,177,235)
Ending balance at Sep. 30, 2019	(306,854)		$ 230	$ (23,417)	149,598	0	(433,265)	35,546	10,642	24,904
Beginning balance (in shares) at Mar. 31, 2019		214,637,925
Beginning balance at Mar. 31, 2019		$ 323,793
Ending balance (in shares) at Jun. 30, 2019		214,637,925
Ending balance at Jun. 30, 2019		$ 323,793
Beginning balance (in shares) at Mar. 31, 2019			75,668,530	(5,177,235)
Beginning balance at Mar. 31, 2019	(319,452)		$ 229	$ (23,417)	147,204	(3)	(443,465)	32,536	7,632	24,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			75,231
Exercise of vested stock options	9		$ 1		8
Stock-based compensation expense	1,316				1,316
Change in net unrealized loss on available for sale investments, at fair value	11					11
Net Loss	(569)						(569)	1,230	1,230
Ending balance (in shares) at Jun. 30, 2019			75,743,761	(5,177,235)
Ending balance at Jun. 30, 2019	$ (318,685)		$ 230	$ (23,417)	148,528	8	(444,034)	33,766	8,862
Ending balance (in shares) at Sep. 30, 2019	214,637,925	214,637,925
Ending balance at Sep. 30, 2019	$ 323,793	$ 323,793
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)			71,040
Exercise of vested stock options	12				12
Stock-based compensation expense	1,058				1,058
Change in net unrealized loss on available for sale investments, at fair value	(8)					(8)
Net Loss	10,769						10,769	1,780	1,780
Ending balance (in shares) at Sep. 30, 2019			75,814,801	(5,177,235)
Ending balance at Sep. 30, 2019	$ (306,854)		$ 230	$ (23,417)	$ 149,598	$ 0	$ (433,265)	$ 35,546	$ 10,642	$ 24,904

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from Operating Activities:
Net Loss	$ (12,514)	$ (43,779)
Adjustments to Reconcile Net Loss to Net Cash Used in Operating Activities:
Change in Fair Value of Financial Instruments, Net	16,259	3,801
Depreciation and Amortization	5,649	7,708
Amortization of Operating Lease Right-of-use Asset	2,469
Gain on Sales of Borrower Loans	(9,237)	(10,658)
Change in Fair Value of Servicing Rights	9,930	9,891
Stock-Based Compensation Expense	3,838	6,412
Restructuring Liability	0	813
Fair Value of Warrants Vested	17,553	55,473
Change in Fair Value of Warrants	(8,890)	(17,885)
Other, Net	369	(873)
Changes in Operating Assets and Liabilities:
Purchase of Loans Held for Sale at Fair Value	(1,809,133)	(1,867,010)
Proceeds from Sales and Principal Payments of Loans Held for Sale at Fair Value	1,656,506	1,751,517
Accounts Receivable	3,449	(4,788)
Prepaid and Other Assets	(4)	1,689
Accounts Payable and Accrued Liabilities	452	2,915
Payable to Investors	(14,031)	(8,316)
Other Liabilities	(3,245)	(3,134)
Net Cash Used in Operating Activities	(140,580)	(116,224)
Cash Flows from Investing Activities:
Purchase of Borrower Loans Held at Fair Value	(127,524)	(134,671)
Principal Payments of Borrower Loans Held at Fair Value	179,298	133,945
Purchases of Property and Equipment	(7,657)	(4,239)
Purchases of Available for Sale Investments, at Fair Value	(1,488)	(14,841)
Maturities of Available for Sale Investments	22,263	40,000
Net Cash Provided by Investing Activities	64,892	20,194
Cash Flows from Financing Activities:
Proceeds from Issuance of Notes Held at Fair Value	128,152	134,490
Payments of Notes Held at Fair Value	(126,721)	(134,943)
Principal Payments on Notes Issued by Securitization Trust	(83,419)	0
Principal Payments on Certificates Issued by Securitization Trust	(8,445)	0
Proceeds from Securitization Issuance	5,642	0
Proceeds from Revolving Debt Facilities	173,611	103,097
Payment for Debt Issuance Costs	(6,614)	(1,428)
Proceeds from Exercise of Warrants and Stock Options	25	31
Net Cash Provided by Financing Activities	82,231	101,247
Net Increase in Cash, Cash Equivalents and Restricted Cash	6,543	5,217
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	207,059	198,463
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	213,602	203,680
Supplemental Disclosure of Cash Flow Information:
Cash Paid for Interest	44,253	33,895
Non-Cash Investing Activity - Accrual for Property and Equipment, Net	516	619
Non-Cash Investing Activity - Consolidation of Borrower Loans, at Fair Value	(262,565)	0
Non-Cash Financing Activity - Issuance of Securitization Notes and Certificates	395,544	0
Non-Cash Financing Activity - Derecognition of Warehouse Line Debt	(130,322)	0
Prosper Funding LLC
Cash flows from Operating Activities:
Net Loss	4,301	520
Adjustments to Reconcile Net Loss to Net Cash Used in Operating Activities:
Change in Fair Value of Financial Instruments, Net	337	614
Other Non-Cash Changes in Borrower Loans, Loans Held for Sale and Notes	(312)	(310)
Depreciation and Amortization	3,279	4,282
Gain on Sales of Borrower Loans	(10,232)	(11,345)
Change in Fair Value of Servicing Rights	10,552	9,973
Changes in Operating Assets and Liabilities:
Purchase of Loans Held for Sale at Fair Value	(1,809,133)	(1,867,010)
Proceeds from Sales and Principal Payments of Loans Held for Sale at Fair Value	1,809,133	1,867,019
Other Assets	(324)	(138)
Accounts Payable and Accrued Liabilities	(3,182)	842
Payable to Investors	(9,495)	(8,241)
Net Related Party Receivable/Payable	360	696
Other Liabilities	46	725
Net Cash Used in Operating Activities	(4,670)	(2,373)
Cash Flows from Investing Activities:
Purchase of Borrower Loans Held at Fair Value	(127,522)	(134,671)
Principal Payments of Borrower Loans Held at Fair Value	125,592	133,945
Purchases of Property and Equipment	(2,854)	(2,547)
Net Cash Provided by Investing Activities	(4,784)	(3,273)
Cash Flows from Financing Activities:
Proceeds from Issuance of Notes Held at Fair Value	128,152	134,490
Payments of Notes Held at Fair Value	(126,721)	(134,943)
Net Cash Provided by Financing Activities	1,431	(453)
Net Increase in Cash, Cash Equivalents and Restricted Cash	(8,023)	(6,099)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	147,181	148,315
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	139,158	142,216
Supplemental Disclosure of Cash Flow Information:
Cash Paid for Interest	29,568	31,222
Non-Cash Investing Activity - Accrual for Property and Equipment, Net	$ 32	$ (6)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Basis of Presentation	Basis of Presentation Prosper Marketplace, Inc. (“PMI”) was incorporated in the state of Delaware on March 22, 2005. Except as the context requires otherwise, as used in these notes to the condensed consolidated financial statements of PMI, “Prosper,” “we,” “us,” and “our” refer to PMI and its wholly-owned subsidiaries, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018. The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. The preparation of Prosper’s condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in Prosper’s financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions. The accompanying interim condensed consolidated financial statements include the accounts of PMI, its wholly-owned subsidiaries and consolidated variable interest entities ("VIEs"). All intercompany balances have been eliminated in consolidation. Securitization Notes are notes held by certain third party investors pursuant to Prosper’s securitization transactions, and are distinguishable from the borrower payment dependent Notes available to investors through our Note Channel.
Prosper Funding LLC
Entity Information [Line Items]
Basis of Presentation	Basis of Presentation Prosper Funding LLC (“PFL”) was formed in the state of Delaware on February 17, 2012 as a limited liability company with the sole equity member being Prosper Marketplace, Inc. (“PMI”). Except as the context otherwise requires, as used in these Notes to the condensed consolidated financial statements of Prosper Funding LLC, “Prosper Funding,” “we,” “us,” and “our” refers to PFL and its wholly owned subsidiaries, Prosper Asset Holdings LLC (“PAH”), a Delaware limited liability company, and Prosper Depositor LLC, a Delaware limited liability company, on a consolidated basis. PAH was dissolved on November 28, 2018. As a result, references to Prosper Funding do not include PAH for periods subsequent to the year ended December 31, 2018. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018. The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. Prosper Funding did not have any items of other comprehensive income (loss) during any of the periods presented in the condensed consolidated financial statements as of and for the nine months ended September 30, 2019 and September 30, 2018. The preparation of Prosper Funding's condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in its condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions, and the differences could be material.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Prosper’s significant accounting policies are included in Note 2 – Summary of Significant Accounting Policies in Prosper’s Annual Report on Form 10-K for the year ended December 31, 2018. There have been no changes to these accounting policies during the first nine months of 2019 other than the changes noted below. Fair Value Measurements Financial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Available for Sale Investments at Fair Value, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors, Convertible Preferred Stock Warrant Liability, Certificates Issued by Securitization Trust and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short term nature. Restricted Cash Restricted Cash consists primarily of cash deposits and short term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors or Prosper have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor. The following table provides a reconciliation of Cash, Cash Equivalents, and Restricted Cash reported within the condensed consolidated balance sheets that sum to the total of the same such amount shown in the condensed consolidated statements of cash flows: September 30, 2019 December 31, 2018 September 30, 2018 December 31, 2017 Cash and Cash Equivalents $ 55,300 $ 57,945 $ 58,447 $ 45,795 Restricted Cash 158,302 149,114 145,233 152,668 Total Cash, Cash Equivalents and Restricted Cash shown in the consolidated statements of cash flows $ 213,602 $ 207,059 $ 203,680 $ 198,463 Borrower Loans, Loans Held for Sale and Notes Through the Note Channel, Prosper purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes issued through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans funded and Notes issued through the Note Channel are carried on Prosper’s condensed consolidated balance sheets as assets and liabilities, respectively. We choose to measure certain financial instruments and certain other items at fair value on an instrument-by-instrument basis with unrealized gains and losses on items for which the fair value option has been elected reported in earnings. Management believes that the fair value option is more meaningful for the readers of the financial statements and it allows both the Borrower Loans and Notes to be valued using the same methodology. The fair value election, with respect to an item, may not be revoked once an election is made. Prosper estimates the fair value of such Borrower Loans and Notes using discounted cash flow methodologies that take into account expected prepayments, losses, recoveries and default rates. The Borrower Loans are not derecognized when a corresponding Note is issued as Prosper maintains the ability to sell the Borrower Loans without the approval of the holders of the corresponding Notes. Leases We determine if an arrangement is a lease at inception. Operating lease right-of-use (“ROU”) assets and operating lease liabilities are included on our condensed consolidated balance sheets in the Property and Equipment, Net and the Other Liabilities sections, respectively. If a contract contains a lease, we evaluate whether it should be classified as an operating or finance lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For certain leases with original terms of twelve months or less we recognize the lease expense as incurred and we do not recognize ROU assets and lease liabilities. Consolidation of Variable Interest Entities The determination of whether to consolidate a variable interest entity (“VIE”) in which we have a variable interest requires a significant amount of analysis and judgment regarding whether we are the primary beneficiary of a VIE due to our holding a controlling financial interest in the VIE. A controlling financial interest in a VIE exists if we have both the power to direct the VIE’s activities that most significantly affect the VIE’s economic performance and a potentially significant economic interest in the VIE. The determination of whether an entity is a VIE considers factors, such as (i) whether the entity’s equity investment at risk is insufficient to allow the entity to finance its activities without additional subordinated financial support and (ii) whether a holder’s equity investment at risk lacks any of the following characteristics of a controlling financial interest: the direct or indirect ability through voting rights or similar rights to make decisions about a legal entity’s activities that have a significant effect on the entity’s success, the obligation to absorb the expected losses of the entity or the right to receive the expected residual returns of the legal entity. Management regularly reviews and reconsiders its previous conclusions regarding the status of an entity as a VIE and whether we are required to consolidate such VIE in the consolidated financial statements. Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period In June 2018, the FASB issued ASU No. 2018-07, "Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting." The ASU is intended to reduce the cost and complexity and to improve financial reporting for nonemployee share-based payments. The ASU expands the scope of Topic 718, Compensation-Stock Compensation, which currently only includes share-based payments to employees, to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. Prosper adopted the standard effective January 1, 2019. The adoption of this standard did not have a material impact on Prosper’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)," which requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases, along with additional qualitative and quantitative disclosures. Prosper adopted the standard effective January 1, 2019. In accordance with ASU 2018-11, "Leases (Topic 842), Target Improvements", Prosper has elected not to restate prior periods and has presented the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings on January 1, 2019. The standard had a material impact on our consolidated balance sheets, but did not materially impact our consolidated statement of operations. The most significant impact is the recognition of ROU assets and lease obligation liabilities for operating leases. Additionally, Prosper recorded an impairment charge to its ROU asset upon adoption due to existing sublease arrangements that were entered into at a loss. The impairment charge did not have a material impact as it will be offset by a reduction of the existing restructuring liability for those leases. Prosper has elected the package of practical expedients, which allows us not to reassess (1) whether any expired or existing contracts as of the adoption date are or contain a lease, (2) lease classification for any expired or existing leases as of the adoption date and (3) initial direct costs for any existing leases as of the adoption date. We did not elect to apply the hindsight practical expedient when determining lease term and assessing impairment of right-of-use assets. We also elected a practical expedient that allowed us to not separate non-lease components from lease components and instead to account for each lease and non-lease component as a single lease component. The adoption of ASU 2016-02 on January 1, 2019 resulted in the recognition of ROU assets of approximately $16.1 million, lease liabilities for operating leases of approximately $21.6 million, a reduction in existing other liabilities of $5.1 million related to deferred rent and restructuring liabilities, and no cumulative-effect adjustment on retained earnings on Prosper's Consolidated Balance Sheets, with no material impact to its Consolidated Statements of Operations. Accounting Standards Issued, To Be Adopted By Prosper In Future Periods In June 2016, the FASB amended guidance related to impairment of financial instruments as part of ASU 2016-13, "Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments", which will be effective for interim and annual periods beginning after December 15, 2019. For loans accounted for at amortized cost, the guidance replaces the incurred loss impairment methodology with an expected credit loss model for which a company recognizes an allowance based on the estimate of expected credit loss. Because Prosper accounts for Borrower Loans at fair value through net income, Prosper expects no impact on its loan portfolios upon adoption. For certain available for sale investments, the guidance will require recognition of expected credit losses through recording an allowance for credit losses. The recognition of this allowance is limited to the difference between the security’s amortized cost basis and fair value. Prosper does not expect the targeted amendments to the available for sale debt securities impairment model to have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment." The standard eliminates Step 2 from the goodwill impairment test, which requires a hypothetical purchase price allocation. Prosper will continue to have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The standard is effective for interim and annual periods beginning after December 15, 2019 and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The standard should be applied on a prospective basis. Prosper does not expect the adoption of this guidance to impact its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement." Entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but public companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU No. 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, but entities are permitted to early adopt either the entire standard or only the provisions that eliminate or modify the requirements. The guidance only affects disclosures in the notes to the consolidated financial statements and will not affect Prosper’s balance sheet or statements of operations. In August 2018, the FASB issued ASU No. 2018-15, "Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract." This ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year and early adoption is permitted. Prosper will prospectively capitalize all eligible costs related to cloud computing arrangements starting January 1, 2020. In March 2019, the FASB issued ASU No. 2019-01, "Leases (Topic 842): Codification Improvements." This ASU aligns the fair value treatment of the underlying asset by lessors that are not manufacturers or dealers as defined under Topic 842, presentation on the Statement of Cash Flows for sales and direct financing leases, and a clarification of interim disclosure requirements in the year of adoption, among other things. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year and early adoption is permitted. Prosper is currently evaluating the impact of this accounting standard update on its consolidated financial statements.
Prosper Funding LLC
Entity Information [Line Items]
Summary of Significant Accounting Policies	Significant Accounting Policies Prosper Funding's significant accounting policies are included in Note 2 – Summary of Significant Accounting Policies in Prosper Funding’s Annual Report on Form 10-K for the year ended December 31, 2018. There have been no changes to these accounting policies during the first nine months of 2019. Fair Value Measurements Financial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Short Term Investments, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short term nature. Restricted Cash Restricted cash consists primarily of cash deposits and short term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors or Prosper has on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amount shown in the condensed consolidated statements of cash flows: September 30, 2019 December 31, 2018 September 30, 2018 December 31, 2017 Cash and Cash Equivalents $ 13,716 $ 11,163 $ 9,643 $ 8,223 Restricted Cash 125,442 136,018 132,573 140,092 Total Cash, Cash Equivalents and Restricted Cash show in the condensed consolidated statements of cash flows $ 139,158 $ 147,181 $ 142,216 $ 148,315 Borrower Loans, Loans Held for Sale and Notes Through the Note Channel, Prosper Funding purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes funded through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans and Notes funded through the Note Channel are carried on Prosper Funding’s condensed consolidated balance sheets as assets and liabilities, respectively. We choose to measure certain financial instruments and certain other items at fair value on an instrument-by-instrument basis with unrealized gains and losses on items for which the fair value option has been elected reported in earnings. Management believes that the fair value option is more meaningful for the readers of the financial statements and it allows both the Borrower Loans and Notes to be valued using the same methodology. The fair value election, with respect to an item, may not be revoked once an election is made. Prosper Funding estimates the fair value of such Borrower Loans and Notes using discounted cash flow methodologies that take into account expected prepayments, losses, recoveries and default rates. The Borrower Loans are not derecognized when a corresponding Note is issued as Prosper Funding maintains the ability to sell the Borrower Loans without the approval of the holders of the corresponding Notes. Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period No accounting standards were adopted in the current period for Prosper Funding LLC. Accounting Standards Issued, To Be Adopted By Prosper Funding In Future Periods In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement." Entities will no longer be required to disclose the amount of and reasons for transfers between level 1 and level 2 of the fair value hierarchy, but public companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for level 3 fair value measurements. ASU No. 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, but entities are permitted to early adopt either the entire standard or only the provisions that eliminate or modify the requirements. The guidance only affects disclosures in the notes to the consolidated financial statements and will not affect Prosper’s balance sheet or statements of operations.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Property and Equipment, Net	Property and Equipment, Net Property and equipment consist of the following (in thousands): September 30, 2019 December 31, 2018 Property and Equipment: Operating lease right-of-use assets $ 16,138 $ — Computer equipment 12,797 15,193 Internal-use software and website development costs 24,783 22,505 Office equipment and furniture 2,999 3,015 Leasehold improvements 7,158 7,157 Assets not yet placed in service 4,647 2,745 Property and equipment 68,522 50,615 Less accumulated depreciation and amortization (37,223) (35,342) Total Property and Equipment, Net $ 31,299 $ 15,273 Depreciation and amortization expense for Property and Equipment for the three months ended September 30, 2019 and September 30, 2018 was $1.8 million and $2.3 million, respectively. Depreciation and amortization expense for property and equipment for the nine months ended September 30, 2019 and September 30, 2018 was $5.4 million and $7.4 million, respectively. These charges are included in General and Administrative expenses on the condensed consolidated statements of operations. Prosper capitalized internal-use software a nd website development costs in the amount of $2.6 million and $1.5 million for the three months ended September 30, 2019 and September 30, 2018, respectively. We capitalized internal-use software and website development costs in the amount of $6.9 million and $4.0 million for the nine months ended September 30, 2019 and September 30, 2018, respectively. Additionally, disclosures around the operating lease right-of-use ass ets are included in Note 17.
Prosper Funding LLC
Entity Information [Line Items]
Property and Equipment, Net	Property and Equipment Property and equipment consist of the following (in thousands): September 30, 2019 December 31, 2018 Property and equipment: Internal-use software and web site development costs $ 21,558 $ 22,505 Less accumulated depreciation and amortization (16,626) (16,079) Total property and equipment, net $ 4,932 $ 6,426 Depreciation expense for the three months ended September 30, 2019 and September 30, 2018 wa s $1.1 million and $1.3 million, respectively. Depreciation expense for the nine months ended September 30, 2019 and September 30, 2018 was $3.3 million and $4.3 million, respectively.

Borrower Loans, Loans Held for

Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value	Borrower Loans, Loans Held for Sale, and Notes, Held at Fair Value The aggregate principal balances outstanding and fair values of Borrower Loans, Loans Held for Sale, and Notes as of September 30, 2019 and December 31, 2018, are presented in the following table (in thousands): Borrower Loans Notes Loans Held for Sale September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Aggregate principal balance outstanding $ 554,208 $ 269,093 $ (254,369) $ (272,430) $ 231,678 $ 185,657 Fair value adjustments (13,239) (5,571) 6,644 8,427 (34) (1,869) Fair value $ 540,969 $ 263,522 $ (247,725) $ (264,003) $ 231,644 $ 183,788 Borrower Loans At September 30, 2019, outstanding Borrower Loans had original terms to maturity of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.92% , and had various maturity dates through September 2024. At December 31, 2018, outstanding Borrower Loans had original maturities of either 36 or 60 months, had mont hly payments with fixed interest rates ranging from 5.31% to 31.92%, and had various maturity dates through December 2023. Approximately $4.2 million and $0.6 million represents the loss that is attributable to changes in the instrument-specific credit risks related to Borrower Loans that were recorded in the change in fair value during the nine months ending September 30, 2019 and September 30, 2018, respectively, as recorded on the condensed consolidated statement of operations. As of September 30, 2019, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $6.0 million and a fair value of $2.4 million. As of December 31, 2018, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $2.5 million and a fair value of $1.1 million . Prosper places loans on non-accrual status when they are over 120 days past due. As of September 30, 2019 and December 31, 2018, Borrower Loans in non-accrual status had a fair value of $0.6 million a nd $0.3 million, respectively. Loans Held for Sale At September 30, 2019, outstanding Loans Held for Sale had original terms to maturity of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and had various maturity dates through September 2024. At December 31, 2018, outstanding Loans Held for Sale had original terms to maturity of either 36 or 60 months , had monthly payments with fixed interest rates ranging from 5.31% to 31.82% and had various maturity dates through December 2023. Fair value adjustments recorded in earnings on loans invested in by us resulted in a net loss of $34 thousand during the nine months ended September 30, 2019. Interest income earned on Loans Held for Sale by us was $13.1 million and $9.2 million during the nine months ended September 30, 2019 and September 30, 2018, respectively. As of September 30, 2019, Loans Held for Sale that were 90 days or more delinquent, had an aggregate principal amount of $0.5 million and a fair value of $0.2 million . As of December 31, 2018, Loans Held for S ale that were 90 days or more delinquent had an aggregate principal amount of $0.8 million and a fair value of $0.3 million .
Prosper Funding LLC
Entity Information [Line Items]
Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value	Borrower Loans and Notes Held at Fair Value The aggregate principal balances outstanding and fair values of Borrower Loans and Notes as of September 30, 2019 and December 31, 2018, are presented in the following table (in thousands): Borrower Loans Notes September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Aggregate principal balance outstanding $ 251,796 $ 269,093 $ (254,369) $ (272,430) Fair value adjustments (4,078) (5,571) 6,644 8,427 Fair value $ 247,718 $ 263,522 $ (247,725) $ (264,003) At September 30, 2019, outstanding Borrower Loans had original terms to maturity of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.92% and had various maturity dates through September 2024. At December 31, 2018, outstanding Borrower Loans had original maturities of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.92%, and had various maturity da tes through December 2023. Within the change in fair value of Borrower Loans, Prosper Funding recorded a loss of approximately $2.5 million and $0.6 million that is attributable to changes in the credit risks related to Borrower Loans during the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $2.4 million and a fair value of $1.0 million . As of December 31, 2018, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $2.5 million and a fair value of $1.1 million. Prosper Funding places loans on non-accrual status when they are over 120 days past due. As of September 30, 2019 and December 31, 2018, Borrower Loans in non-accrual status had a fair value of $0.3 million a nd $0.3 million, respectively.

Loan Servicing Assets and Liabi

Loan Servicing Assets and Liabilities	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Loan Servicing Assets and Liabilities	Loan Servicing Assets and Liabilities Prosper accounts for servicing assets and liabilities at their estimated fair values with changes in fair values recorded in servicing fees. The initial asset or liability is recognized when Prosper sells Borrower Loans to unrelated third-party buyers through the Whole Loan Channel and the servicing rights are retained. The servicing assets and liabilities are measured at fair value throughout the servicing period. The total gains and losses recognized on the sale of such Borrower Loans for the three months ended September 30, 2019 was a gain of $2.6 million an d no gain or loss was recognized from the Fair Value of Warrants Vested on the Sale of Borrower Loans to the Consortium. The total gains recognized on the sale of such Borrower Loans were $3.1 million during the three months ended September 30, 2018, and a loss of $19.6 million from the Fair Value of Warrants Vested on the Sale of Borrower Loans to the Consortium. The total gains and losses recognized on the sale of such Borrower Loans for the nine months ended September 30, 2019 was a gain of $8.8 million and a loss of $17.6 million from the Fair Value of Warrants Vested on the Sale of Borrower Loans to the Consortium. The total gains recognized on the sal e of such Borrower Loans were $10.7 million during the nine months ended September 30, 2018, and a loss of $55.5 million from the Fair Value of Warrants Vested on the Sale of Borrower Loans to the Consortium. As of September 30, 2019, Borrower Loans that were sold but for which Prosper retained servicing rights had a total outstanding principal balance of $3.2 billion, original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.92%, and various maturity dates through September 2024. A t December 31, 2018, Borrower Loans that were sold but for which Prosper retained servicing rights had a total outstanding principal balance of $3.6 billion, original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 35.52%, and various maturity dates through December 2023. $27.8 million and $32.5 million of contractually specified servicing fees and ancillary fees are included on our condensed consolidated statements of operations in Servicing Fees, Net for the nine months ended September 30, 2019 and September 30, 2018, respectively. Fair Value Valuation Method . Prosper uses a discounted cash flow valuation methodology generally consisting of developing an estimate of future cash flows that are expected to occur over the life of a financial instrument and then discounting those cash flows at a rate of return that results in the fair value amount. Significant unobservable inputs presented in the table within Note 8 below are those that Prosper considers significant to the estimated fair values of the level 3 servicing assets and liabilities. The following is a description of the significant unobservable inputs provided in the table. Market Servicing Rate . Prosper estimates adequate market servicing rates that would fairly compensate a substitute servicer should one be required, which includes the profit that would be demanded in the marketplace. This rate is stated as a fixed percentage of outstanding principal balance on a per annum basis. Prosper estimated these market servicing rates based on observable market rates for other loan types in the industry and bids from subservicing providers, adjusted for the unique loan attributes that are present in the specific loans that Prosper sells and services and information from a backup service provider. Discount Rate . The discount rate is a rate of return used to discount future expected cash flows to arrive at a present value, which represents the fair value of the loan servicing rights. We used a range of discount rates for the servicing assets and liabilities based on comparable observed valuations of similar assets and publicly available disclosures related to servicing valuations, with comparability adjustments made to account for differences with Prosper’s servicing assets. Default Rate . The default rate presented in Note 8 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional default rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to default per period based on the term and age of the underlying Borrower Loans. The assumption regarding defaults directly reduces servicing revenues because the amount of servicing revenues received is based on the amount collected each period. Prepayment Rate . The prepayment rate presented in Note 8 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional prepayment rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to prepay per period based on the term and age of the underlying Borrower Loans. Prepayments reduce servicing revenues as they shorten the period over which we expect to collect fees on the Borrower Loans, which is used to project future servicing revenues.
Prosper Funding LLC
Entity Information [Line Items]
Loan Servicing Assets and Liabilities	Loan Servicing Assets and Liabilities Prosper Funding accounts for servicing assets and liabilities at their estimated fair values with changes in fair values recorded in servicing fees. The initial asset or liability is recognized when Prosper Funding sells Borrower Loans to unrelated third-party buyers through the Whole Loa n Channel and the servicing rights are retained. The total gains or losses recognized on the sale of such Borrower Loans were a gain of $3.2 million and a loss of $16.4 million for the three months ended September 30, 2019 and September 30, 2018, respectively. The total losses recognized on the sale of such Borrower Loans were a loss of $7.7 million and $44.1 million for the nine months ended September 30, 2019 and September 30, 2018, respectively. As of September 30, 2019, Borrower Loans that were sold, but for which Prosper Funding retained servicing rights, had a total outstanding principal balance of $3.8 billion, original terms of either 36 or 60 months , monthly payments with fixed interest rates ranging from 5.31% to 31.92% , and various maturity dates th rough September 2024. At December 31, 2018, Borrower Loans that were sold, but for which Prosper Funding retained servicing rights, had a total outstanding principal balance of $3.7 billion, original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 35.52%, and various maturity dates through December 2023. $10.7 million and $11.3 million of contractually specified servicing fees and ancillary fees are included on our condensed consolidated statements of operations in Servicing Fees, Net for the three months ended September 30, 2019 and September 30, 2018, respectively. $31.0 million and $33.1 million of contractually specified servicing fees and ancillary fees are included on our condensed consolidated statements of operations in Servicing Fees, Net for the nine months ended September 30, 2019 and September 30, 2018, resp ectively. Fair Value Valuation Method . Prosper Funding uses a discounted cash flow valuation methodology generally consisting of developing an estimate of future cash flows that are expected to occur over the life of a financial instrument and then discounting those cash flows at a rate of return that results in the fair value amount. Significant unobservable inputs presented in the table within Note 7 below are those that Prosper Funding considers significant to the estimated fair values of the level 3 servicing assets and liabilities. The following is a description of the significant unobservable inputs provided in the table. Market Servicing Rate . Prosper Funding estimates adequate market servicing rates that would fairly compensate a substitute servicer should one be required, which includes the profit that would be demanded in the marketplace. This rate is stated as a fixed percentage of outstanding principal balance on a per annum basis. Prosper Funding estimated these market servicing rates based on observable market rates for other loan types in the industry and bids from subservicing providers, adjusted for the unique loan attributes that are present in the specific loans that Prosper Funding sells and services and information from a backup service provider. Discount Rate . The discount rate is a rate of return used to discount future expected cash flows to arrive at a present value, which represents the fair value of the loan servicing rights. We used a range of discount rates for the servicing assets and liabilities based on comparable observed valuations of similar assets and publicly available disclosures related to servicing valuations, with comparability adjustments made to account for differences with Prosper Funding’s servicing assets. Default Rate . The default rate presented in Note 7 is an annualized, average estimate considering all Borrower Loan categories (i.e. risk ratings and duration), and represents an aggregate of conditional default rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to default per period based on the term and age of the underlying Borrower Loans. The assumption regarding defaults directly reduces servicing revenues because the amount of servicing revenues received is based on the amount collected each period.

Available for Sale Investments,

Available for Sale Investments, at Fair Value	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Available for Sale Investments, at Fair Value	Available for Sale Investments, at Fair Value Available for sale investments are recorded at fair value and unrealized gains and losses are reported, net of taxes, in accumulated other comprehensive income (loss) included in stockholders' equity unless management determines that an investment is other-than-temporarily impaired. The amortized cost, gross unrealized gains and losses, and fair value of available for sale investments as of September 30, 2019 and December 31, 2018, are as follows (in thousands): September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturity securities: Treasury Bills $ — $ — $ — $ — US Treasury securities 1,500 — — 1,500 Total Available for Sale Investments $ 1,500 $ — $ — $ 1,500 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturity securities: Treasury Bills $ 17,940 $ — $ (3) $ 17,937 US Treasury securities 4,246 — (10) 4,236 Total Available for Sale Investments $ 22,186 $ — $ (13) $ 22,173 We did not hold any available for sale investments with unrealized losses as of September 30, 2019. A summary of available for sale investments with unrealized losses as of December 31, 2018, aggregated by category and period of contin uous unrealized loss, is as follows (in thousands): Less than 12 months 12 months or longer Total December 31, 2018 Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Fixed maturity securities: Treasury Bills $ 17,937 $ (3) $ — $ — $ 17,937 $ (3) US Treasury securities — — 4,236 (10) 4,236 (10) Total Investments with Unrealized Losses $ 17,937 $ (3) $ 4,236 $ (10) $ 22,173 $ (13) There were no impairment charges recognized during the nine months ended September 30, 2019 and 2018. The maturities of available for sale investments at September 30, 2019 and December 31, 2018 are as follows (in thousands): September 30, 2019 Within 1 year After 1 year through 5 years After 5 years to 10 years After 10 years Total Treasury Bills $ — $ — $ — $ — $ — US Treasury securities 1,500 — — — 1,500 Total Fair Value $ 1,500 $ — $ — $ — $ 1,500 Total Amortized Cost $ 1,500 $ — $ — $ — $ 1,500 December 31, 2018 Within 1 year After 1 year through 5 years After 5 years to 10 years After 10 years Total Treasury Bills $ 17,937 $ — $ — $ — $ 17,937 US Treasury securities 4,236 — — — 4,236 Total Fair Value $ 22,173 $ — $ — $ — $ 22,173 Total Amortized Cost $ 22,186 $ — $ — $ — $ 22,186 No investments were sold during the nine months ended September 30, 2019 and 2018.

Securitization

Securitization	9 Months Ended
	Sep. 30, 2019
Transfers and Servicing [Abstract]
Securitization and Variable Interest Entities	Securitizations PMIT 2019-1 On February 7, 2019, we completed a securitization of approximately $205.1 million in unsecured personal whole loans facilitated through our platform through a securitization trust ("PMIT 2019-1") which we consolidated. PMIT 2019-1 issued notes, residual certificates and a risk retention interest to finance the purchase of Borrower Loans. The resulting notes were sold to third party investors for $171.7 million in net proceeds. Prosper retained 65.5% of the resulting residual certificates. The remaining residual certificates and the risk retention interests are held by third party investors. PMIT 2019-1 was deemed a VIE that we consolidate because we are the primary beneficiary of the VIE. The creditors of PMIT 2019-1 have no recourse to the general credit of PMI as the primary beneficiary of the VIEs and the liabilities of the VIEs can only be settled by the respective VIE’s assets. Additionally, Prosper's continued involvement includes loan servicing responsibilities over the life of the underlying loans. As a result, we have included PMIT 2019-1's Borrower Loans under "Borrower Loans, at Fair Value," the notes held by third party investors under "Notes Issued by Securitization Trust" and the risk retention and residual certificates held by third party investors under "Certificates Issued by Securitization Trust, at Fair Value" in our condensed consolidated balance sheets. The notes under the PMIT 2019-1 securitization were issued in three classes: Class A in the amount of $127.3 million, Class B in the amount of $25.0 million and Class C in the amount of $19.3 million (collectively, the “2019-1 Notes”). The Class A, Class B and Class C notes bear interest at a fixed rate of 3.54%, 4.03% and 5.27%, respectively. Principal and interest payments began in March 2019 and are payable monthly. These notes are recorded at amortized cost on the balance sheet. The associated debt issuance costs of $2.3 million are deferred and amortized into interest expense over the contractual life of the notes. The notes held by third-party investors and the unamortized debt issuance costs are included in “Notes Issued by Securitization Trust” with a balance of $115.6 million on the condensed consolidated balance sheets as of September 30, 2019 and are secured by Borrower Loans at fair value of $128.5 million included in “Borrower Loans, at Fair Value” on the condensed consolidated balance sheets as of September 30, 2019 . The risk retention and residual certificates are carried at fair value and the risk retention interest represents the right to receive 5.0% of all amounts collected on the Borrower Loans held by PMIT 2019-1, net of its pro-rata share of ongoing fees and expenses of PMIT 2019-1. PMIT 2019-2 On May 23, 2019, we completed a securitization of approximately $203.5 million in unsecured personal whole loans facilitated through our platform through a securitization trust ("PMIT 2019-2") which we consolidated. PMIT 2019-2 issued notes, residual certificates and a risk retention interest to finance the purchase of Borrower Loans. The resulting notes were sold to third party investors for $174.2 million in net proceeds. Prosper retained 16.4% of the resulting residual certificates. The remaining residual certificates and the risk retention interests are held by third party investors. PMIT 2019-2 was deemed a VIE that we consolidate because we are the primary beneficiary of the VIE. The creditors of PMIT 2019-2 have no recourse to the general credit of PMI as the primary beneficiary of the VIEs and the liabilities of the VIEs can only be settled by the respective VIE’s assets. Additionally, Prosper's continued involvement includes loan servicing responsibilities over the life of the underlying loans. As a result, Prosper has included PMIT 2019-2's Borrower Loans under "Borrower Loans, at Fair Value", the notes held by third party investors under "Notes Issued by Securitization Trust" and the risk retention and residual certificates held by third party investors under "Certificates Issued by Securitization Trust, at Fair Value" in Prosper's condensed consolidated balance sheets. The notes under the PMIT 2019-2 securitization were issued in three classes: Class A in the amount of $110.1 million, Class B in the amount of $31.4 million and Class C in the amount of $32.7 million (collectively, the “2019-2 Notes”). The Class A, Class B and Class C notes bear interest at a fixed rate of 3.20%, 3.69% and 5.05%, respectively. Principal and interest payments begin in July 2019 and are payable monthly. These notes are recorded at amortized cost on the balance sheet. The associated debt issuance costs of $1.9 million are deferred and amortized into interest expense over the contractual life of the notes. The notes held by third-p arty investors and the unamortized debt issuance costs are included in “Notes Issued by Securitization Trust” with a balance of $144.5 million on the condensed consolidated balance sheets as of September 30, 2019 and are secured by Borrower Loans at fair value of $164.8 million of included in “Borrower Loans, at Fair Value” on the condensed consolidated balance sheets as of September 30, 2019 . The risk retention and residual certificates are carried at fair value and the risk retention interest represents the right to receive 5.0% of all amounts collected on the Borrower Loans held by PMIT 2019-2, net of its pro-rata share of ongoing fees and expenses of PMIT 2019-2.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities Prosper measures the fair value of assets and liabilities in accordance with its fair value hierarchy which prioritizes information used to measure fair value and the effect of fair value measurements on earnings and provides for enhanced disclosures determined by the level within the hierarchy of information used in the valuation. We apply this framework whenever other standards require (or permit) assets or liabilities to be measured at fair value. Assets and liabilities carried at fair value on the balance sheets are classified among three levels based on the observability of the inputs used to determine fair value: Level 1 — The valuation is based on quoted prices in active markets for identical instruments. Level 2 — The valuation is based on observable inputs such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation methodologies for which all significant assumptions are observable in the market. Level 3 — The valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the instrument. Level 3 valuations are typically performed using pricing models, discounted cash flow methodologies, or similar methodologies, which incorporate management’s own estimates of assumptions that market participants would use in pricing the instrument or valuations that require significant management judgment or estimation. Fair values of assets or liabilities are determined based on the fair value hierarchy, which requires an entity to maximize the use of quoted prices and observable inputs and to minimize the use of unobservable inputs when measuring fair value. Various valuation methodologies are utilized, depending on the nature of the financial instrument, including the use of market prices for identical or similar instruments, or discounted cash flow models. When possible, active and observable market data for identical or similar financial instruments are utilized. Alternatively, fair value is determined using assumptions that management believes a market participant would use in pricing the asset or liability. Financial Instruments Recorded at Fair Value The fair value of the Borrower Loans, Loans Held for Sale, Certificates Issued by Securitization Trust and Notes are estimated using discounted cash flow methodologies based upon a set of valuation assumptions. The primary cash flow assumptions used to value such Borrower Loans, Loans Held for Sale, Certificates Issued by Securitization Trust, and Notes include default rates derived from historical performance and discount rates applied to each credit grade based on the perceived credit risk of each credit grade. Investments held at fair value consist of Available for Sale Investments. The Available for Sale Investments may consist of corporate debt securities, commercial paper, U.S. Treasury securities, Treasury bills, agency bonds and short term bond funds. When available, Prosper uses quoted prices in active markets to measure the fair value of securities available for sale. When utilizing market data and bid-ask spreads, Prosper uses the price within the bid-ask spread that best represents fair value. When quoted prices do not exist, Prosper uses prices obtained from independent third-party pricing services to measure the fair value of investment assets. Prosper's primary independent pricing service provides prices based on observable trades and discounted cash flows that incorporate observable information, such as yields for similar types of securities (a benchmark interest rate plus observable spreads) and weighted-average maturity for the same or similar securities. Prosper compares the prices obtained from its primary independent pricing service to the prices obtained from the additional independent pricing services to determine if the price obtained from the primary independent pricing service is reasonable. Prosper does not adjust the prices received from independent third-party pricing services unless such prices are inconsistent with the definition of fair value and result in a material difference in the recorded amounts. The Convertible Preferred Stock Warrant Liability is valued using a Black-Scholes option pricing model. Refer to Note 13 for further details. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2019 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 540,969 $ 540,969 Loans Held for Sale — — 231,644 231,644 Available for Sale Investments, at Fair Value — 1,500 — 1,500 Servicing Assets — — 12,936 12,936 Total Assets $ — $ 1,500 $ 785,549 $ 787,049 Liabilities: Notes $ — $ — $ 247,725 $ 247,725 Servicing Liabilities — — 2 2 Certificates Issued by Securitization Trust, at Fair Value — — 37,564 37,564 Convertible Preferred Stock Warrant Liability — — 152,342 152,342 Loan Trailing Fee Liability — — 3,281 3,281 Total Liabilities $ — $ — $ 440,914 $ 440,914 December 31, 2018 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 263,522 $ 263,522 Loans Held for Sale — — 183,788 183,788 Available for Sale Investments, at Fair Value — 22,173 — 22,173 Servicing Assets — — 14,687 14,687 Total Assets $ — $ 22,173 $ 461,997 $ 484,170 Liabilities: Notes $ — $ — $ 264,003 $ 264,003 Servicing Liabilities — — 12 12 Convertible Preferred Stock Warrant Liability — — 143,679 143,679 Loan Trailing Fee Liability — — 3,118 3,118 Total Liabilities $ — $ — $ 410,812 $ 410,812 As Prosper’s Borrower Loans, Loans Held for Sale, Certificates Issued by Securitization Trust, Notes, and loan servicing rights do not trade in an active market with readily observable prices, Prosper uses significant unobservable inputs to measure the fair value of these assets and liabilities. Financial instruments are categorized in the level 3 valuation hierarchy based on the significance of unobservable factors in the overall fair value measurement. These fair value estimates may also include observable, actively quoted components derived from external sources. As a result, the realized and unrealized gains and losses for assets and liabilities within the level 3 category may include changes in fair value that were attributable to both observable and unobservable inputs. Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs used for Prosper’s level 3 fair value measurements at September 30, 2019 and December 31, 2018: Borrower Loans, Loans Held for Sale and Notes: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 4.7% - 12.3% 4.7% - 13.8% Default rate 2.1% - 18.4% 2.0% - 15.8% Servicing Rights: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% Market servicing rate 0.625 % 0.625 % Loan Trailing Fee Liability: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% At September 30, 2019, the discounted cash flow methodology used to estimate the Note fair values used the same projected cash flows as the related Borrower Loans. The following tables present additional information about level 3 Borrower Loans, Loans Held for Sale and Notes measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Certificates Issued by Securitization Trust Loans Held for Sale Total Balance at July 1, 2019 $ 606,799 $ (253,425) $ (44,090) $ 114,962 $ 424,246 Purchase of Borrower Loans/Issuance of Notes 41,460 (41,439) — 647,896 647,917 Principal repayments (87,348) 40,993 4,173 (19,580) (61,762) Borrower Loans sold to third parties (1,526) — — (511,596) (513,122) Other changes 240 (65) 252 832 1,259 Change in fair value (18,656) 6,211 2,101 (870) (11,214) Balance at September 30, 2019 $ 540,969 $ (247,725) $ (37,564) $ 231,644 $ 487,324 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2018 $ 277,361 $ (277,425) $ 116,817 $ 116,753 Purchase of Borrower Loans/Issuance of Notes 43,596 (43,797) 542,910 542,709 Principal repayments (42,139) 43,418 (13,105) (11,826) Borrower Loans sold to third parties (843) — (530,496) (531,339) Other changes 24 (9) 73 88 Change in fair value (9,450) 9,225 (3,004) (3,229) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 113,195 $ 113,156 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Certificates Issued by Securitization Trust Loans Held for Sale Total Balance at January 1, 2019 $ 263,522 $ (264,003) $ — $ 183,788 $ 183,307 Purchase of Borrower Loans/Issuance of Notes 390,089 (128,152) (51,595) 1,809,133 2,019,475 Transfers in (Transfers out) 147,773 — — (147,773) — Principal repayments (221,379) 126,721 8,445 (46,109) (132,322) Borrower Loans sold to third parties (3,412) — — (1,564,904) (1,568,316) Other changes 331 538 (351) 921 1,439 Change in fair value (35,955) 17,171 5,937 (3,412) (16,259) Balance at September 30, 2019 $ 540,969 $ (247,725) $ (37,564) $ 231,644 $ 487,324 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2018 $ 293,005 $ (293,948) $ 49 $ (894) Purchase of Borrower Loans/Issuance of Notes 134,671 (134,490) 1,867,010 1,867,191 Principal repayments (131,086) 134,943 (27,370) (23,513) Borrower Loans sold to third parties (2,859) — (1,724,147) (1,727,006) Other changes (314) 624 869 1,179 Change in fair value (24,868) 24,283 (3,216) (3,801) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 113,195 $ 113,156 The following tables present additional information about level 3 servicing assets measured at fair value on a recurring basis (in thousands): Servicing Fair Value at July 1, 2019 $ 13,387 Additions 2,859 Less: Changes in fair value (3,310) Fair Value at September 30, 2019 $ 12,936 Servicing Fair Value at July 1, 2018 15,644 Additions 3,156 Less: Changes in fair value (3,362) Fair Value at September 30, 2018 $ 15,438 Servicing Assets Fair Value at January 1, 2019 $ 14,687 Additions 9,237 Derecognition (1,049) Less: Changes in fair value (9,939) Fair Value at September 30, 2019 $ 12,936 Servicing Assets Fair Value at January 1, 2018 $ 14,711 Additions 10,658 Derecognition — Less: Changes in fair value (9,931) Fair Value at September 30, 2018 $ 15,438 The following table presents additional information about level 3 Preferred Stock Warrant Liability measured at fair value on a recurring basis (in thousands): Preferred Stock Balance as of July 1, 2019 $ 166,559 Add Issuances of Preferred Stock Warrant — Change in Fair Value of the Preferred Stock Warrant Liability (14,217) Balance as of September 30, 2019 $ 152,342 Preferred Stock Balance as of July 1, 2018 $ 143,676 Add Issuances of Preferred Stock Warrant 19,561 Change in Fair Value of the Preferred Stock Warrant Liability (9,283) Balance as of September 30, 2018 $ 153,954 Preferred Stock Balance as of January 1, 2019 $ 143,679 Add Issuances of Preferred Stock Warrant 17,553 Change in Fair Value of the Preferred Stock Warrant Liability (8,890) Balance as of September 30, 2019 $ 152,342 Preferred Stock Balance as of January 1, 2018 $ 116,366 Add Issuances of Preferred Stock Warrant 55,473 Change in Fair Value of the Preferred Stock Warrant Liability (17,885) Balance as of September 30, 2018 $ 153,954 Loan Trailing Fee The fair value of the Loan Trailing Fee represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and defaults rates using a discounted cash flow model. The following table presents additional information about level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Balance at January 1, 2019 $ 3,118 Issuances 2,063 Cash Payment of Loan Trailing Fee (1,744) Change in Fair Value (156) Balance at September 30, 2019 $ 3,281 Significant Recurring Level 3 Fair Value Asset and Liability Input Sensitivity Key economic assumptions and the sensitivity of the current fair value to immediate changes in those assumptions at September 30, 2019 for Borrower Loans, Loans Held for Sale and Notes funded through the Note Channel are presented in the following table (in thousands, except percentages): Borrower Loans and Loans Held for Sale Notes Fair Value as of September 30, 2019 $ 772,613 $ 247,725 Discount rate assumption: 7.03 % * 6.90 % * Resulting fair value from: 100 basis point increase $ 765,521 $ 245,448 200 basis point increase $ 758,597 $ 243,225 Resulting fair value from: 100 basis point decrease $ 779,880 $ 250,059 200 basis point decrease $ 787,326 $ 252,450 Default rate assumption: 12.27 % * 13.50 % * Resulting fair value from: 100 basis point increase $ 762,459 $ 244,453 200 basis point increase $ 752,608 $ 241,278 Resulting fair value from: 100 basis point decrease $ 782,961 $ 251,059 200 basis point decrease $ 793,379 $ 254,417 * Represents weighted average assumptions considering all credit grades. The following table presents the estimated impact on Prosper’s estimated fair value of servicing assets, calculated using different market servicing rates and different default rates as of September 30, 2019 (in thousands, except percentages). Servicing Assets Fair Value as of September 30, 2019 $ 12,936 Market servicing rate assumptions 0.625 % Resulting fair value from: Market servicing rate increase to 0.65% $ 12,148 Market servicing rate decrease to 0.60% $ 13,758 Weighted average prepayment assumptions 21.49 % Resulting fair value from: Applying a 1.1 multiplier to prepayment rate $ 12,781 Applying a 0.9 multiplier to prepayment rate $ 13,127 Weighted average default assumptions 12.70 % Resulting fair value from: Applying a 1.1 multiplier to default rate $ 12,793 Applying a 0.9 multiplier to default rate $ 13,116 These sensitivities are hypothetical and should be evaluated with care. The effect on fair value of a variation in assumptions generally cannot be determined because the relationship of the change in assumptions to the fair value may not be linear. Additionally, the impact of a variation in a particular assumption on the fair value is calculated while holding other assumptions constant. In reality, changes in one factor may lead to changes in other factors, which could impact the above hypothetical effects. Financial Instruments, Assets and Liabilities not Recorded at Fair Value The following table presents the fair value hierarchy for financial instruments, assets, and liabilities not recorded at fair value (in thousands): September 30, 2019 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 55,300 $ 55,300 $ — $ — $ 55,300 Restricted Cash 158,302 — 158,302 — 158,302 Accounts Receivable 1,670 — 1,670 — 1,670 Total Assets $ 215,272 $ 55,300 $ 159,972 $ — $ 215,272 Liabilities: Accounts Payable and Accrued Liabilities $ 20,305 $ — $ 20,305 $ — $ 20,305 Payable to Investors 113,507 — 113,507 — 113,507 Notes Issued by Securitization Trust 260,060 — 265,207 — 265,207 Warehouse Lines 205,818 — 205,818 — 205,818 Total Liabilities $ 599,690 $ — $ 604,837 $ — $ 604,837
Prosper Funding LLC
Entity Information [Line Items]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities Prosper Funding measures the fair value of assets and liabilities in accordance with its fair value hierarchy which prioritizes information used to measure fair value and the effect of fair value measurements on earnings and provides for enhanced disclosures determined by the level within the hierarchy of information used in the valuation. We apply this framework whenever other standards require (or permit) assets or liabilities to be measured at fair value. Assets and liabilities carried at fair value on the balance sheets are classified among three levels based on the observability of the inputs used to determine fair value: Level 1 — The valuation is based on quoted prices in active markets for identical instruments. Level 2 — The valuation is based on observable inputs such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation methodologies for which all significant assumptions are observable in the market. Level 3 — The valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the instrument. Level 3 valuations are typically performed using pricing models, discounted cash flow methodologies, or similar methodologies, which incorporate management’s own estimates of assumptions that market participants would use in pricing the instrument or valuations that require significant management judgment or estimation. Fair values of assets or liabilities are determined based on the fair value hierarchy, which requires an entity to maximize the use of quoted prices and observable inputs and to minimize the use of unobservable inputs when measuring fair value. Various valuation methodologies are utilized, depending on the nature of the financial instrument, including the use of market prices for identical or similar instruments, or discounted cash flow models. When possible, active and observable market data for identical or similar financial instruments are utilized. Alternatively, fair value is determined using assumptions that management believes a market participant would use in pricing the asset or liability. Financial Instruments Recorded at Fair Value The fair value of the Borrower Loans, Loans Held for Sale and Notes are estimated using discounted cash flow methodologies based upon a set of valuation assumptions. The primary cash flow assumptions used to value such Borrower Loans, Loans Held for Sale and Notes include default rates derived from historical performance and discount rates applied to each credit grade based on the perceived credit risk of each credit grade. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2019 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 247,718 $ 247,718 Servicing Assets — — 15,220 15,220 Total Assets $ — $ — $ 262,938 $ 262,938 Liabilities: Notes $ — $ — $ 247,725 $ 247,725 Servicing Liabilities — — 2 2 Loan Trailing Fee Liability — — 3,281 3,281 Total Liabilities $ — $ — $ 251,008 $ 251,008 December 31, 2018 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 263,522 $ 263,522 Servicing Assets — — 15,550 15,550 Total Assets $ — $ — $ 279,072 $ 279,072 Liabilities: Notes $ — $ — $ 264,003 $ 264,003 Servicing Liabilities — — 12 12 Loan Trailing Fee Liability — — 3,118 3,118 Total Liabilities $ — $ — $ 267,133 $ 267,133 As Prosper Funding’s Borrower Loans, Loans Held for Sale, Notes and loan servicing rights do not trade in an active market with readily observable prices, Prosper Funding uses significant unobservable inputs to measure the fair value of these assets and liabilities. Financial instruments are categorized in the level 3 valuation hierarchy based on the significance of unobservable factors in the overall fair value measurement. These fair value estimates may also include observable, actively quoted components derived from external sources. As a result, the realized and unrealized gains and losses for assets and liabilities within the level 3 category may include changes in fair value that were attributable to both observable and unobservable inputs. Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs used for Prosper Funding’s level 3 fair value measurements at September 30, 2019 and December 31, 2018: Borrower Loans and Notes: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 4.7% - 12.2% 4.7% - 13.8% Default rate 2.3% - 17.7% 2.0% - 15.8% Servicing Assets and Liabilities: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% Market servicing rate 0.625 % 0.625 % Loan Trailing Fee Liability: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% The changes in the Borrower Loans, Loans Held for Sale and Notes, which are level 3 assets and liabilities measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2019 $ 254,070 $ (253,425) $ — $ 645 Originations 41,460 (41,439) 647,896 647,917 Principal repayments (40,600) 40,993 — 393 Borrower Loans sold to third parties (855) — (647,896) (648,751) Other changes (26) (65) — (91) Change in fair value (6,331) 6,211 — (120) Balance at September 30, 2019 $ 247,718 $ (247,725) $ — $ (7) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2018 $ 277,361 $ (277,425) $ 31 $ (33) Originations 43,596 (43,797) 542,910 542,709 Principal repayments (42,139) 43,418 (6) 1,273 Borrower Loans sold to third parties (843) — (542,899) (543,742) Other changes 24 (9) — 15 Change in fair value (9,450) 9,225 (25) (250) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 11 $ (28) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2019 $ 263,522 $ (264,003) $ — $ (481) Originations 127,522 (128,152) 1,809,133 1,808,503 Principal repayments (123,014) 126,721 — 3,707 Borrower Loans sold to third parties (2,578) — (1,809,133) (1,811,711) Other changes (226) 538 — 312 Change in fair value (17,508) 17,171 — (337) Balance at September 30, 2019 $ 247,718 $ (247,725) $ — $ (7) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2018 $ 293,005 $ (293,948) $ 49 $ (894) Originations 134,671 (134,490) 1,867,010 1,867,191 Principal repayments (131,086) 134,943 (20) 3,837 Borrower Loans sold to third parties (2,859) — (1,866,999) (1,869,858) Other changes (314) 624 — 310 Change in fair value (24,868) 24,283 (29) (614) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 11 $ (28) The following table presents additional information about level 3 servicing assets recorded at fair value (in thousands): Servicing Assets Fair Value at July 1, 2019 $ 15,461 Additions 3,436 Less: Changes in fair value (3,677) Fair Value at September 30, 2019 $ 15,220 Servicing Assets Fair Value at July 1, 2018 $ 16,162 Additions 3,198 Less: Changes in fair value (3,430) Fair Value at September 30, 2018 $ 15,930 Servicing Assets Fair Value at January 1, 2019 $ 15,550 Additions 10,232 Less: Changes in fair value (10,562) Fair Value at September 30, 2019 $ 15,220 Servicing Assets Fair Value at January 1, 2018 $ 14,598 Additions 11,345 Less: Changes in fair value (10,013) Fair Value at September 30, 2018 $ 15,930 Loan Trailing Fee The fair value of the Loan Trailing Fee represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and defaults rates using a discounted cash flow model. The following table presents additional information about level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Liability Fair Value at January 1, 2019 $ 3,118 Issuances 2,063 Cash payment of Loan Trailing Fee (1,744) Change in fair value (156) Fair Value at September 30, 2019 $ 3,281 Significant Recurring Level 3 Fair Value Asset and Liability Input Sensitivity Key economic assumptions and the sensitivity of the current fair value to immediate changes in those assumptions at September 30, 2019 for Borrower Loans, Loans Held for Sale and Notes funded are presented in the following table (in thousands, except percentages): Borrower Loans Notes Fair Value at September 30, 2019 $ 247,718 $ 247,725 Discount rate assumption: 6.90 % * 6.90 % * Resulting fair value from: 100 basis point increase $ 245,444 $ 245,448 200 basis point increase $ 243,224 $ 243,225 Resulting fair value from: 100 basis point decrease $ 250,048 $ 250,059 200 basis point decrease $ 252,435 $ 252,450 Default rate assumption: 13.50 % * 13.50 % * Resulting fair value from: 100 basis point increase $ 244,463 $ 244,453 200 basis point increase $ 241,304 $ 241,278 Resulting fair value from: 100 basis point decrease $ 251,036 $ 251,059 200 basis point decrease $ 254,376 $ 254,417 * Represe nts weighted average assumptions considering all credit grades. The following table presents the estimated impact on Prosper Funding’s estimated fair value of servicing assets, calculated using different market servicing rates and different default rates as of September 30, 2019 (in thousands, except percentages): Servicing Assets Fair Value at September 30, 2019 $ 15,220 Market servicing rate assumptions 0.625 % Resulting fair value from: Market servicing rate increase to 0.65% $ 14,274 Market servicing rate decrease to 0.60% $ 16,167 Weighted average prepayment assumptions 21.49 % Resulting fair value from: Applying a 1.1 multiplier to prepayment rate $ 14,557 Applying a 0.9 multiplier to prepayment rate $ 14,952 Weighted average default assumptions 12.70 % Resulting fair value from: Applying a 1.1 multiplier to default rate $ 15,033 Applying a 0.9 multiplier to default rate $ 15,412 These sensitivities are hypothetical and should be evaluated with care. The effect on fair value of a 10% variation in assumptions generally cannot be determined because the relationship of the change in assumptions to the fair value may not be linear. Additionally, the impact of a variation in a particular assumption on the fair value is calculated while holding other assumptions constant. In reality, changes in one factor may lead to changes in other factors, which could impact the above hypothetical effects.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill Prosper’s goodwill balance of $36.4 million at September 30, 2019 did not change during the nine months ended September 30, 2019. We did not record any goodwill impa irment expense for the nine months ended September 30, 2019. Other Intangible Assets The following table presents the detail of other intangible assets for the period presented (dollars in thousands): September 30, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value Remaining Useful Life (In Years) Developed technology $ 3,060 $ (3,060) $ — — User base and customer relationships 5,050 (4,261) 789 5.6 Brand name 60 (60) — — Total Intangible Assets Subject to Amortization $ 8,170 $ (7,381) $ 789 Prosper’s intangible asset balance w as $0.8 million and $1.0 million at September 30, 2019 and December 31, 2018, respectively. The user base and customer relationships intangible assets are being amortized on an accelerated basis over a three ten Amortization expense for the three months ended September 30, 2019 and September 30, 2018 was $0.1 million and $0.1 million, respectively. Amortization expense for the nine months ended September 30, 2019 and September 30, 2018 was $0.2 million and $0.3 million, respe ctively. Estimated amortization of purchased intangible assets for future periods is as follows (in thousands): Year Ending December 31, Estimated Amortization of Purchased Intangible Assets 2019 (remainder thereof) $ 70 2020 219 2021 172 2022 136 2023 107 Thereafter 85 Total $ 789

Other Liabilities

Other Liabilities	9 Months Ended
	Sep. 30, 2019
Other Liabilities [Abstract]
Other Liabilities	Other Liabilities Other Liabilities includes the following: September 30, 2019 December 31, 2018 Loan trailing fee $ 3,281 $ 3,118 Deferred revenue 297 396 Servicing liabilities 2 12 Deferred income tax liability 392 373 Deferred rent — 3,408 Restructuring liability — 2,106 Operating lease liability 18,570 — Other 1,023 1,216 Total Other Liabilities $ 23,565 $ 10,629 Additionally, disclosures around the operating lease liabilities are included in Note 17.

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt PWIT Warehouse Line On January 19, 2018, through a wholly-owned subsidiary, Prosper Warehouse I Trust ("PWIT"), Prosper entered into an agreement (the "Warehouse Agreement") for a committed revolving line of credit (the "PWIT Warehouse Line"). PWIT was deemed a VIE that we consolidate because Prosper is the primary beneficiary of the VIE. In connection with the Warehouse Agreement, PWIT entered into a security agreement with a bank as administrative agent and a national banking association as collateral trustee and paying agent. Proceeds under the PWIT Warehouse Line may only be used to purchase certain unsecured consumer loans and related rights and documents from us and to pay fees and expenses related to the PWIT Warehouse Line. Effective June 12, 2018 the Warehouse Agreement was amended. The amendments included increasing the committed line of credit from $100 million to $200 million, extending the term of the Warehouse line (including the final maturity date), amending the monthly unused commitment fee, and reducing the rate at which the PWIT Warehouse Line bears interest. Subsequently the Warehouse Agreement was amended on June 20, 2019 to extend the facility, reduce the interest rate and unused commitment fee, and expand the eligibility criteria for unsecured consumer loans that can be financed through the PWIT Warehouse Line. Under the amended agreement, proceeds of loans made under the PWIT Warehouse Line may be borrowed, repaid, and reborrowed until the earlier of June 20, 2021 and the occurrence of any accelerated amortization event or event of default. Repayment of any outstanding proceeds will be made over the 24 month period ending June 20, 2023, excluding the occurrence of any accelerated amortization event or event of default. Under the amended agreement, the PWIT Warehouse Line bears interest at a rate of LIBOR plus 2.90% and h as an advance rate of 89%. Additionally, the PWIT Warehouse Line bears a monthly unused commitment fee of 0.50% per annum on the undrawn portion available under the Warehouse Line. The Warehouse Agreement contains certain covenants applicable to PWIT, including restrictions on PWIT’s ability to incur indebtedness, pledge assets, merge or consolidate, and enter into certain affiliate transactions. The Warehouse Line also requires Prosper to maintain a minimum tangible net worth of $25 million, minimum net liquidity of $15 million and a maximum leverage ratio of 5:1. Tangible net worth is defined as the sum of (i) (A) convertible preferred stock, (B) total stockholders’ deficit and (C) convertible preferred stock warrant liability, less the sum of (ii) (A) goodwill and (B) intangible assets. Net liquidity is defined as the sum of cash, cash equivalents and available for sale investmen ts. The leverage ratio is defined as the ratio of total consolidated indebtedness other than non-recourse securitization indebtedness, non-recourse or limited recourse warehouse indebtedness, and borrower payment dependent Notes, to tangible net worth. As of September 30, 2019, Prosper was in compliance with the covenants under the Warehouse Agreement. As of September 30, 2019, Prosper had $110.1 million i n debt outstanding and accrued interest under the PWIT Warehouse Line. This debt is secured by an aggregate outstanding principal balance o f $124.2 million i ncluded in Loans Held for Sale, at Fair Value on the condensed consolidated balance sheet. At September 30, 2019 the undrawn portion available under the PWIT Warehouse Line w as $89.9 million. Pro sper incurred $1.8 million o f capitalized debt issuance costs, which will be recognized as interest expense throu gh June 20, 2023. Prosper has also purchased swaptions to limit our exposure to increases in LIBOR. The swaptions are recorded on the condensed consolidated balance sheet at fair value in Prepaids and Other Assets. Any changes in the fair value are recorded in the Change in Fair Value of Financial Instruments, Net on the condensed consolidated statement of operations. The fair value of the swaptions was not material at September 30, 2019. PWIIT Warehouse Line On March 28, 2019, through a wholly-owned subsidiary, Prosper Warehouse II Trust ("PWIIT"), Prosper entered into an agreement (the "PWIIT Warehouse Agreement") for a $300 million committed revolving line of credit (the "PWIIT Warehouse Line" and, together with the PWIT Warehouse Line, the "Warehouse Lines"), with a different national banking association than PWIT. PWIIT was deemed a VIE that we consolidate because Prosper is the primary beneficiary of the VIE. In connection with the PWIIT Warehouse Agreement, PWIIT entered into a security agreement with a bank as administrative agent and a national banking association as collateral trustee and paying agent. Proceeds under the PWIIT Warehouse Line may only be used to purchase certain unsecured consumer loans and related rights and documents from us and to pay fees and expenses related to the PWIIT Warehou se Line. Under the agreement, proceeds of loans made under the PWIIT Warehouse Line may be borrowed, repaid, and reborrowed until the earlier of March 28, 2021 and the occurrence of any accelerated amortization event or event of default. Repayment of any outstanding proceeds will be made over the 24 month period ending March 28, 2023, excluding the occurrence of any accelerated amortization event or event of default. Under the agreement, the PWIIT Warehouse Line bears interest at a rate of LIBOR or the lender's asset-backed commercial paper rate plus a spread of 2.90%. The spread increases by 0.375% during the first 12 months immediately following the termination of the revolving period with an additional increase of 0.375% one year later. The PWIIT Warehouse Line has an advance rate of 90%. Additionally, the PWIIT Warehouse Line bears a monthly unused commitment fee of 0.50% per annum on the undrawn portion available under the PWIIT Warehouse Line. The PWIIT Warehouse Agreement contains certain covenants applicable to PWIIT, including restrictions on PWIIT’s ability to incur indebtedness, pledge assets, merge or consolidate, and enter into certain affiliate transactions. The PWIIT Warehouse Line also requires Prosper to maintain a minimum tangible net worth of $25 million, minimum net liquidity of $15 million and a maximum leverage ratio of 5:1. Tangible net worth is defined as the sum of (i) (A) convertible preferred stock, (B) total stockholders’ deficit and (C) convertible preferred stock warrant liability, less the sum of (ii) (A) goodwill and (B) intangible assets. Net liquidity is defined as the sum of cash, cash equivalents and available for sale investments. The leverage ratio is defined as the ratio of total consolidated indebtedness other than non-recourse securitization indebtedness, non-recourse or limited recourse warehouse indebtedness, and borrower dependent notes, to tangible net worth. As of September 30, 2019, Prosper was in compliance with the covenants under the PWIIT Warehouse Agreement. As of September 30, 2019, Prosper had $95.7 million in debt outstanding and accrued interest under the PWIIT Warehouse Line. This debt is secured by an aggregate outstanding principal balance of $106.0 million included in Loans Held for Sale, at Fair Value on the condensed consolidated balance sheet. At September 30, 2019 the undrawn portion available under the PWIIT Warehouse Line was $204.3 million. Prosper incurred $2.1 million of capitalized debt issuance costs, which will be recognized as interest expense through March 28, 2023.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Loss Per Share	Net Income (Loss) Per Share We compute earnings per share using the two-class method. The two-class method allocates earnings that otherwise would have been available to common shareholders to holders of participating securities. We consider all series of our convertible preferred stock to be participating securities due to their rights to participate in dividends with common stock. As such, earnings allocated to these participating securities, which include participation rights in undistributed earnings, are subtracted from net income to determine total undistributed earnings to be allocated to common stockholders. Basic and diluted net income (loss) per share was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net income (loss) $ 10,769 $ (19,779) $ (12,514) $ (43,779) Less: net income allocated to participating securities (7,994) — — — Net income (loss) available to common stockholders $ 2,775 $ (19,779) $ (12,514) $ (43,779) Denominator: Weighted average shares used in computing net income (loss) per share - basic 70,606,805 70,394,269 70,532,641 70,353,819 Effect of dilutive securities: Stock options 1,939,105 — — — Convertible preferred stock warrants 213,264,845 — — — Weighted average shares used in computing diluted net income (loss) per share - diluted 285,810,755 70,394,269 70,532,641 70,353,819 Net income (loss) per share - basic $ 0.04 $ (0.28) $ (0.18) $ (0.62) Net income (loss) per share - diluted $ 0.01 $ (0.28) $ (0.18) $ (0.62) The following common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (shares) (shares) (shares) (shares) Excluded securities: Convertible preferred stock issued and outstanding 214,637,925 214,637,925 214,637,925 214,637,925 Stock options issued and outstanding 73,211,425 67,566,031 73,029,965 69,486,992 Warrants issued and outstanding 1,080,349 1,080,349 1,080,349 1,082,055 Series E-1 convertible preferred stock warrants 35,544,141 35,544,141 35,544,141 35,544,141 Series F convertible preferred stock warrants 177,720,704 177,720,704 177,720,704 177,720,704 Total common stock equivalents excluded from diluted net loss per common share computation 502,194,544 496,549,150 502,013,084 498,471,817

Convertible Preferred Stock, Wa

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit	Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit Convertible Preferred Stock and Warrants Under PMI’s amended and restated certificate of incorporation, preferred stock is issuable in series, and the Board of Directors is authorized to determine the rights, preferences, and terms of each series. The number of authorized, issued and outstanding shares, their par value and liquidation preference for each series of convertible preferred stock as of September 30, 2019 are disclosed in the table below (amounts in thousands except share and per share amounts): Convertible Preferred Stock Par Value Authorized Shares Outstanding and Issued Shares Liquidation Preference (Outstanding Shares) Series A $ 0.01 68,558,220 68,558,220 $ 19,774 Series A-1 $ 0.01 24,760,915 24,760,915 49,522 Series B $ 0.01 35,775,880 35,775,880 21,581 Series C $ 0.01 24,404,770 24,404,770 70,075 Series D $ 0.01 23,888,640 23,888,640 165,000 Series E-1 $ 0.01 35,544,141 — — Series E-2 $ 0.01 16,858,078 — — Series F $ 0.01 177,720,707 3 — Series G $ 0.01 37,249,497 37,249,497 50,000 444,760,848 214,637,925 $ 375,952 Dividends Dividends on shares of the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F and Series G convertible preferred stock are payable only when, as, and if declared by the Board of Directors. No dividends will be paid with respect to the common stock until any declared dividends on the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stock have been paid or set aside for payment to the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stockholders. After payment of any such dividends, any additional dividends or distributions will be distributed among all holders of common stock and preferred stock in proportion to the number of shares of common stock that would be held by each such holder if all shares of preferred stock were converted to common stock at the then-effective conversion rate. The Series A-1 convertible preferred shares have no dividend rights. To date, no dividends have been declared on any of the PMI’s preferred stock or common stock. Conversion Under the terms of PMI’s amended and restated certificate of incorporation, the holders of preferred stock have the right to convert such preferred stock into common stock at any time. In addition, all preferred stock automatically converts into common stock (i) immediately prior to the closing of an initial public offering that values Prosper at least at $2 billion and that results in aggregate proceeds to Prosper of at least $100 million or (ii) upon a written request from the holders of at least 60% of the voting power of the outstanding preferred stock (on an as-converted basis), provided that (i) the Series A-1 convertible preferred stock shall not be converted without at least 14% of the voting power of the outstanding Series A-1 convertible preferred stock; (ii) the Series D shall not be converted without at least 60% of the voting power of the outstanding Series D; (iii) the Series E-1 and Series E-2 shall not be converted without at least 60% of the voting power of the outstanding Series E-1 and Series E-2, voting together as a single class; (iv) the Series F shall not be converted without at least 60% of the voting power of the outstanding Series F, and (v) the shares of Series G Preferred Stock will not be automatically converted unless the holders of at least 60% of the outstanding shares of Series G Preferred Stock approve such conversion. In addition, if a holder of the Series A convertible preferred stock has converted any of the Series A convertible preferred stock, then all of such holder’s shares of Series A-1 convertible preferred stock also will be converted upon a liquidation event. In lieu of any fractional shares of common stock to which a holder would otherwise be entitled, PMI shall pay such holder cash in an amount equal to the fair market value of such fractional shares, as determined by its Board of Directors. At present, each of the Series A, Series B, Series C, Series D, Series E-1, Series E-2, and Series F convertible preferred stock converts into PMI common stock at a 1:1 ratio. The Series A-1 convertible preferred stock converts into common stock at a 1,000,000:1 ratio and the Series G convertible preferred stock converts into common stock at a 1:1.36 ratio. The Series G convertible preferred stock conversion ratio reflects the Series G true-up that occurred at end of the vesting period for the Series E-2 and Series F Preferred Stock warrants. Liquidation Rights PMI’s convertible preferred stock has been classified as temporary equity on the condensed consolidated balance sheets. The preferred stock is not redeemable; however, in the event of a voluntary or involuntary liquidation, dissolution, change in control or winding up of PMI, holders of the convertible preferred stock may have the right to receive its liquidation preference under the terms of PMI’s certificate of incorporation. Each holder of Series E-1, Series E-2, and Series F convertible preferred stock is entitled to receive prior and in preference to any distribution of proceeds from a liquidation event to the holders of Series A, Series B, Series C, Series D, Series G and Series A-1 convertible preferred stock or common stock, an amount per share for (i) each share of Series E-1 convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, (ii) each share of Series E-2 convertible preferred stock equal to the sum of two-thirds the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, and (iii) each share of Series F convertible preferred stock equal to the sum of two-thirds of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series E-1, Series E-2, and Series F convertible preferred stock, each holder of Series A, Series B, Series C and Series D, Series E-2, Series F, and Series G convertible preferred stock is entitled to receive, on a pari passu basis, prior to and in preference to any distribution of proceeds from a liquidation event to the holders of Series A-1 convertible preferred stock or common stock, (i) an amount per share for each share of Series E-2 and Series F convertible preferred stock equal to the sum of one-third of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, and (ii) an amount per share for each share of Series A, Series B, Series C, Series D and Series G convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stock, the holders of Series A-1 convertible preferred stock are entitled to receive, prior and in preference to any distribution of proceeds to the holders of common stock, an amount per share for each such share of Series A-1 convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, Series G, and Series A-1 convertible preferred stock, the entire remaining proceeds legally available for distribution will be distributed pro rata to the holders of Series A convertible preferred stock and common stock in proportion to the number of shares of common stock held by them assuming the Series A convertible preferred stock has been converted into shares of common stock at the then effective conversion rate, provided that the maximum aggregate amount per share of Series A convertible preferred stock which the holders of Series A convertible preferred stock shall be entitled to receive is three times the original issue price for the Series A convertible preferred stock. At present, the liquidation preferences are equal to $0.29 per share for the Series A convertible preferred stock, $2.00 per share for the Series A-1 convertible preferred stock, $0.60 per share for the Series B convertible preferred stock, $2.87 per share for the Series C convertible preferred stock, $6.91 per share for the Series D convertible preferred stock, $0.84 per share for the Series E-1 convertible preferred stock, $0.84 per share for the Series E-2 convertible preferred stock, $0.84 per share for the Series F convertible preferred stock and $1.34 per share for the Series G convertible preferred stock. Voting Each holder of shares of convertible preferred stock is entitled to the number of votes equal to the number of shares of common stock into which such shares of convertible preferred stock could be converted and has voting rights and powers equal to the voting rights and powers of the common stock. The holders of convertible preferred stock and the holders of common stock vote together as a single class (except with respect to certain matters that require separate votes or as required by law), and are entitled to notice of any stockholders’ meeting in accordance with the Bylaws of PMI. Convertible Preferred Stock Warrant Liability Series E-1 Warrants In connection with the Settlement and Release Agreement dated November 17, 2016 among PMI, PFL and Colchis, on December 16, 2016, PMI issued the First Series E-1 Warrant. The Second Series E-1 Warrant for an additional 15,277,006 shares of Series E-1 convertible preferred stock was granted on the signing of the Consortium Purchase Agreement (as defined in Note 16) on February 27, 2017. The warrants expire ten years from the dat e of issuance. For the three months ended September 30, 2019 and 2018, Prosper recognized $1.8 million and $2.1 million of income, respectively, from the re-measurement of the fair value of the warrants. For the nine months ended September 30, 2019, Prosper recognized $0.7 million and $4.6 million of income, respectively, from the re-measurement of the fair value of the warrants. The income or expense resulted from the remeasurement of the fair value of the warrants is recorded through change in fair value of convertible preferred stock warrants in the condensed consolidated statement of operations. To determine the fair value of the Series E-1 Warrants, we first determined the value of a share of a Series E-1 convertible preferred stock. To determine the fair value of the convertible preferred stock, we first derived the business enterprise value (“BEV”) of Prosper using valuation methods, including a combination of methods, as deemed appropriate under the circumstances applicable at the valuation date. Once we determined an estimated BEV, the option pricing method ("OPM") was used to allocate the BEV to the various classes of our equity, including our preferred stock. The concluded per share value for the Series E-1 convertible preferred stock was utilized as an input to the Black-Scholes option pricing model. We determined the fair value of the outstanding Series E-1 Warrants utilizing the following assumptions as of the following dates: September 30, 2019 December 31, 2018 Volatility 40% 40% Risk-free interest rate 1.63% 2.62% Remaining contractual term 7.29 years 8.04 years Dividend yield —% —% The above assumptions were determined as follows: Volatility . The volatility is derived from historical volatilities of several unrelated publicly listed peer companies over a period approximately equal to the term of the warrant because we have limited information on the volatility of the preferred stock since there is currently no trading history. When making the selections of industry peer companies to be used in the volatility calculation, we considered the size, operational, and economic similarities to our principal business operations. Risk-Free Interest Rate . The risk-free interest rate is based on the U.S. Treasury yield in effect as of the period end date and for zero coupon U.S. Treasury notes with maturities approximately equal to the term of the warrant. Remaining Contractual Term . The remaining contractual term represents the time from the date of the valuation to the expiration of the warrant. Dividend Yield . The expected dividend assumption is based on our current expectations about our anticipated dividend policy. Series F Warrants In connection with the Consortium Purchase Agreement (as described in Note 16), PMI issued warrants to purchase up to 177,720,706 shares of PMI's Series F convertible preferred stock at $0.01 per share. For the three months ended September 30, 2019 and 2018, Prosper recognized $12.4 million and $7.2 million of income, respectively, from the re-measurement of the fair value of the warrants. For the nine months ended September 30, 2019, Prosper recognized $8.1 million and $13.3 million of income, respectively, from the re-measurement of the fair value of the warrants. The income is recorded through change in fair value of convertible preferred stock warrants in the condensed consolidated statement of operations. To determine the fair value of the Series F Warrants, we first determined the value of a share of a Series F convertible preferred stock. To determine the fair value of the convertible preferred stock, we first derived the BEV using valuation methods, including a combination of methods, as deemed appropriate under the circumstances applicable at the valuation date. Once we determined an estimated BEV, the OPM was used to allocate the BEV to the various classes of Prosper's equity, including our preferred stock. The concluded per share value for the Series F convertible preferred stock warrants utilized the Black-Scholes option pricing model. We determined the fair value of the outstanding Series F Warrants utilizing the following assumptions as of the following dates: September 30, 2019 December 31, 2018 Volatility 40% 40% Risk-free interest rate 1.63% 2.63% Remaining contractual term 7.41 years 8.16 years Dividend yield —% —% The above assumptions were determined as follows: Volatility . The volatility is derived from historical volatilities of several unrelated publicly listed peer companies over a period approximately equal to the term of the warrant because we have limited information on the volatility of the preferred stock since there is currently no trading history. When making the selections of industry peer companies to be used in the volatility calculation, we considered the size, operational, and economic similarities to our principal business operations. Risk-Free Interest Rate . The risk-free interest rate is based on the U.S. Treasury yield in effect as of the period end date and for zero coupon U.S. Treasury notes with maturities approximately equal to the term of the warrant. Remaining Contractual Term . The remaining contractual term represents the time from the date of the valuation to the expiration of the warrant. Dividend Yield . The expected dividend assumption is based on our current expectations about our anticipated dividend policy. The combined activity of the Convertible Preferred Stock Warrant Liability for the nine months ended September 30, 2019 and 2018 are as follows (in thousands): Warrant Activity Balance at January 1, 2019 $ 143,679 Warrants Vested 17,553 Change in Fair Value (8,890) Balance at September 30, 2019 $ 152,342 Warrant Activity Balance at January 1, 2018 $ 116,366 Warrants Vested 55,473 Change in Fair Value (17,885) Balance at September 30, 2018 $ 153,954 Common Stock PMI, through its Amended and Restated Certificate of Incorporation, is the sole issuer of common stock and related options, restricted stock units ("RSUs") and warrants. On February 16, 2016, PMI amended and restated its Certificate of Incorporation to, among other things, effect a 5-for-1 forward stock split. On September 20, 2017, PMI further amended its Amended and Restated Certificate of Incorporation to increase the number of shares of common stock authorized for issuance. The total number of shares of stock which PMI has the authority to issue is 1,069,760,848, consisting of 625,000,000 shares of common stock, $0.01 par value per share, and 444,760,848 shares of preferred stock, $0.01 par value per share. As of September 30, 2019, 71,573,501 shares of common stock were issued and 70,637,566 shares of common stock were outstanding. As of December 31, 2018, 71,411,145 shares of common stock were issued and 70,475,210 shares of common stock were outstanding. Each holder of common stock is entitled to one vote for each share of common stock held. Common Stock Issued upon Exercise of Stock Options

Share Based Incentive Plan and

Share Based Incentive Plan and Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Share Based Incentive Plan and Compensation	Share Based Incentive Plan and Compensation PMI grants equity awards primarily through its Amended and Restated 2005 Stock Option Plan (the “2005 Plan”), which was approved as amended and restated by its stockholders on December 1, 2010; and its 2015 Equity Incentive Plan, which was approved by its stockholders on April 7, 2015 and subsequently amended by an Amendment No. 1, Amendment No. 2 and Amendment No. 3, which were approved by PMI's stockholders effective as of February 15, 2016, May 31, 2016, and September 5, 2018 respectively (as amended, the "2015 Plan"). In March 2015, the 2005 Plan expired, except that any awards granted under the 2005 Plan prior to its expiration remain in effect pursuant to their terms. Stock Option Reprice On May 3, 2016, the Compensation Committee of the Board of Directors of PMI approved a stock option repricing program (the “2016 Reprice”), authorizing PMI’s officers to reprice certain outstanding stock options held by employees and directors that have exercise prices above the current fair market value of PMI’s common stock. The repricing was effected on May 16, 2016 for eligible directors and employees located in the United States and on May 19, 2016 for eligible employees located in Israel. On March 17, 2017, the Compensation Committee of the Board of Directors of PMI approved a stock option repricing program (the “2017 Reprice” and together with the 2016 Reprice, the "Repricings"), authorizing PMI’s officers to reprice certain outstanding stock options held by employees and directors that have exercise prices above the current fair market value of PMI’s common stock. The repricing was effected on March 17, 2017 for eligible directors and employees. Prosper believes that the Repricings will encourage the continued service of valued employees and directors, and motivate such service providers to perform at high levels, both of which are critical to Prosper’s continued success. Prosper expects to incur additional stock based compensation charges as a result of the Repricings. The financial statement impact of the above Repricings was $0.1 million and $0.3 million in the three and nine months ended September 30, 2019. As of September 30, 2019, the unamortized Repricings amount (net of forfeitures) was immaterial and will be recognized over the remaining weighted average vesting period of 0.5 years. Stock Option Activity Stock option activity under the 2005 Plan and 2015 Plan is summarized for the nine months ended September 30, 2019 below: Options Issued and Outstanding Weighted- Average Exercise Price Balance as of January 1, 2019 71,021,698 $ 0.33 Options issued 8,999,048 $ 0.28 Options exercised (162,356) $ 0.15 Options forfeited (4,531,344) $ 0.40 Options expired (53,700) $ 0.30 Balance as of September 30, 2019 75,273,346 $ 0.32 Options vested and expected to vest as of September 30, 2019 62,244,684 $ 0.32 Options vested and exercisable at September 30, 2019 49,227,760 $ 0.28 Other Information Regarding Stock Options The weighted-average remaining life for options outstanding as of September 30, 2019 was 7.68 years. The fair value of options granted to employees is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires Prosper to make assumptions and judgments about the variables used in the calculation, including the fair value of PMI’s common stock, the expected term (the period of time that the options granted are expected to be outstanding), the volatility of PMI’s common stock, a risk-free interest rate, and expected dividends. Given the absence of a publicly traded market, Prosper considered numerous objective and subjective factors to determine the fair value of PMI’s common stock at each grant date. These factors included, but were not limited to: (i) contemporaneous valuations of common stock performed by unrelated third-party specialists, (ii) the prices for PMI’s preferred stock sold to outside investors, (iii) the rights, preferences and privileges of PMI’s preferred stock relative to PMI’s common stock, (iv) the lack of marketability of PMI’s common stock, (v) developments in the business, (vi) secondary transactions of PMI’s common and preferred shares, and (vii) the likelihood of achieving a liquidity event, such as an initial public offering or a merger or acquisition of Prosper, given prevailing market conditions. As PMI’s stock is not publicly traded, volatility for stock options is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of Prosper. The expected term assumptions were determined based on the vesting terms, exercise terms and contractual lives of the options using the simplified method. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. Prosper uses an expected dividend yield of zero as it does not anticipate paying any dividends in the foreseeable future. Prosper also estimates forfeitures of unvested stock options. Expected forfeitures are based on Prosper’s historical experience. To the extent actual forfeitures differ from the estimates, the difference will be recorded as a cumulative adjustment in the period estimates are revised. No compensation cost is recorded for options that do not vest. The fair value of PMI’s stock option awards granted during the three and nine months ended September 30, 2019 and September 30, 2018 was estimated at the date of grant using the Black-Scholes model with the following average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Volatility of common stock 46.72 % 43.76 % 46.72 % 44.06 % Risk-free interest rate 1.57 % 2.85 % 2.24 % 2.76 % Expected life 6.0 years 6.0 years 5.9 years 6.0 years Dividend yield — % — % — % — % Restricted Stock Unit Activity During the nine months ended September 30, 2019, PMI did not grant any RSUs to employees. In previous reporting periods, PMI granted certain employees RSUs that are subject to three four The following table summarizes the number of PMI’s outstanding RSUs and their weighted-average grant date fair value during the nine months ended September 30, 2019: Number of Shares Weighted-Average Grant Date Fair Value Unvested - January 1, 2019 4,856,141 $ 0.96 Forfeited (53,000) $ 1.90 Unvested - September 30, 2019 4,803,141 $ 0.95 The following table presents the amount of stock-based compensation related to stock-based awards granted to employees recognized in Prosper’s condensed consolidated statements of operations during the three and nine months ended September 30, 2019 and September 30, 2018 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Origination and servicing $ 73 $ 213 $ 377 $ 670 Sales and marketing 71 108 216 324 General and administrative 844 1,507 3,245 5,418 Total stock based compensation $ 988 $ 1,828 $ 3,838 $ 6,412 Prosper capitalized stock-based compensation as internal use software and website development costs of $0.1 million and $0.1 million during the three months ended September 30, 2019 and September 30, 2018, respectively, and $0.3 million and $0.3 million during the nine months ended September 30, 2019 and September 30, 2018, respectively. As of September 30, 2019 , the unamortized stock- based compensation expense adjusted for forfeiture estimates related to our employees’ unvested stock-based awards was approximately $4.2 million, which will be recognized over the remaining weighted-average vesting period of approximately 2.2 years.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Income Taxes	Income Taxes For the three months ended September 30, 2019 and September 30, 2018, Prosper reco gnized $29 thousand and $8 thousand of income tax expense, respectively. For the nine months ended September 30, 2019 and September 30, 2018, Prosper recognized $87 thousand and $27 thousand of income tax expense, respectively. The income tax expense relates to state income tax expense and the amortization of tax deductible goodwill which gives rise to an indefinite-lived deferred tax liability. No other income tax expense or benefit was recorded for the three or nine month periods ended September 30, 2019 and September 30, 2018 due to a full valuation allowance recorded against our deferred tax assets . Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to utilize our existing deferred tax assets. On the basis of this evaluation, it is not more likely than not that our deferred tax assets will be realized and therefore a full valuation allowance has been recorded.
Prosper Funding LLC
Entity Information [Line Items]
Income Taxes	Income TaxesProsper Funding incurred no income tax provision for the nine months ended September 30, 2019 and September 30, 2018. Prosper Funding is a US disregarded entity and its income and loss is included in the return of its parent, PMI. Since PMI is in a loss position, is not currently subject to income taxes, and has fully reserved its deferred tax asset, the net effective tax rate for Prosper Funding is 0%.

Consortium Purchase Agreement

Consortium Purchase Agreement	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Consortium Purchase Agreement	Consortium Purchase Agreement On February 27, 2017, Prosper entered into a series of agreements (the "Consortium Purchase Agreement") with a consortium of investors (the "Consortium"), pursuant to which the Consortium agreed to purchase Borrower Loans in an aggregate principal amount of up to $5.0 billion (including certain loans purchased by one of the investors prior to the date of the Consortium Purchase Agreement). PFL was obligated to offer for purchase minimum monthly volumes of eligible loans to the Consortium, for the Consortium to elect to purchase. The obligation to offer for purchase minimum monthly volumes of eligible loans and the related vesting ended upon the expiration of the Consortium Purchase Agreement in May 2019. In connection with the Consortium Purchase Agreement, PMI issued to the Consortium three warrants to purchase up to an aggregate 177,720,706 shares of PMI’s Series F Preferred Stock at an exercise price of $0.01 per share (the “Warrant Shares”). The Consortium's right to exercise these Series F Warrants was subject to monthly vesting and was fully vested in May 2019. On vesting of the Series F Warrants, Prosper recorded a liability as "Convertible Preferred Stock Warrant Liability" on the condensed consolidated balance sheets at fair value and a corresponding amount as "Fair Value of Warrants Vested on Sale of Borrower Loans" on the condensed consolidated statement of operations. Subsequent changes in the fair value of the vested warrants are recorded in "Change in Fair Value of Convertible Preferred Stock Warrants" on the condensed consolidated statement of operations. Additionally, in connection with the execution of the Consortium Purchase Agreement, certain previously issued rebates were settled by an issuance of vested Series F Convertible Preferred Stock Warrants. The difference in fair value of these warrants over the cash settlement price is recorded in "Change in Fair Value of Convertible Preferred Stock Warrants" on the condensed consolidated statement of operations. The following represents the loans purchased and warrants vested under the Consortium Purchase Agreement through its expiration in May 2019: Loans Acquired Warrants Vested Balance as of January 1, 2019 $ 3,067,332 $ 154,912,980 Nine Months Ended September 30, 2019 235,951 22,807,726 Balance as of September 30, 2019 $ 3,303,283 $ 177,720,706 In addition to the $3.3 billion of loans acquired above, warrants vested on signing of the Consortium Purchase Agreement were issued to settle certain rebates on $0.3 billion of whole loan purchases by members of the Consortium prior to the signing of the Consortium Purchase Agreement. This $0.3 billion also reduced the up to $5.0 billion aggregate amount under the Consortium Purchase Agreement.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases Prosper has operating leases for corporate offices and datacenters. Our leases have remaining lease terms of one year to eight years. Some of the lease agreements include options to extend the lease term for up to an additional five Operating lease right-of-use ("ROU") assets The following represents the operating lease right-of-use assets as of September 30, 2019, which are included in "Property and Equipment, Net" on the condensed consolidated balance sheets. September 30, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value ROU Assets - Office buildings $ 15,846 $ 2,296 $ 13,550 ROU Assets - Other 292 173 119 Total right-of-use assets subject to amortization $ 16,138 $ 2,469 $ 13,669 Lease Liabilities Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows (in thousands). The present value of the future minimum lease payments represent our lease liabilities as of September 30, 2019 and are included in "Other Liabilities" on the condensed consolidated balance sheets. Minimum Lease Payments Remainder of 2019 $ 1,328 2020 5,240 2021 5,134 2022 5,018 2023 1,567 Thereafter 2,546 Total future minimum lease payments $ 20,833 Less imputed interest (2,263) Present value of future minimum lease payments $ 18,570 The table below presents future minimum rental payments at December 31, 2018, net of minimum sublease rentals of $5.3 million, for the remaining terms of the operating leases (in thousands): 2019 $ 4,536 2020 4,683 2021 4,456 2022 4,319 2023 847 Thereafter 387 Total future operating lease obligations $ 19,228 Because the rate implicit in each lease is not readily determinable, we use our incremental borrowing rate to determine the present value of the lease payments. Other information related to leases was as follows ($ in thousands): September 30, 2019 Cash paid for operating leases year-to-date $ 3,903 Right of use assets obtained in exchange for new operating lease obligations (1) $ 21,630 Weighted average remaining lease term 4.31 years Weighted average discount rate 5.53 % (1) Consists of $21.6 million for operating leases existing on January 1, 2019.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Commitments and Contingencies	Commitments and Contingencies Operating Commitments Prosper entered into an agreement with WebBank, under which all Borrower Loans originated through the marketplace are made by WebBank under its bank charter. Pursuant to the agreement, the marketing fee that Prosper receives in connection with the origination of each loan is partially reduced by an amount (the “Designated Amount”) calculated as a percentage of the principal amount of such loan based on the aggregate principal amount of loans originated for the applicable month. To the extent the aggregate Designated Amount for all loans originated during any month is less than $143,500, Prosper is required to pay WebBank an amount equal to such deficiency. Accordingly, the minimum fee for the remaining three months of 2019 is $0.4 million. The minimum fee is $1.7 million for the years 2020 and 2021, and $0.1 million for the year 2022. Additionally, under the agreement with WebBank, Prosper is required to maintain minimum net liquidity of $15.0 million at all times during the term of the agreement. Net liquidity is defined as the sum of Cash, Cash Equivalents and Available for Sale Investments. Violation of this covenan t can result in termination of the contract with WebBank. As of September 30, 2019, Prosper was in compliance with the covenant. Loan Purchase Commitments Prosper entered into an agreement with WebBank to purchase $33.4 million of Borrower Loans that WebBank originated during the last two business days of the quarter ended September 30, 2019 and the first business day of the quarter ending December 31, 2019. Prosper will purchase these Borrower Loans within the first three business days of the quarter ending December 31, 2019. Repurchase and Indemnification Contingency Under the terms of the loan purchase agreements between Prosper and investors that participate in the Whole Loan Channel, Prosper may, in certain circumstances, become obligated to repurchase a Borrower Loan from an investor. Generally, these circumstances include the occurrence of verifiable identity theft, the failure to properly follow loan listing or bidding protocols, or a violation of the applicable federal, state, or local lending laws. The fair value of the indemnification and repurchase obligation is estimated based on historical experience. Prosper recognizes a liability for the repurchase and indemnification obligation when the Borrower Loans are issued. Indemnified or repurchased Borrower Loans associated with violations of federal, state, or local lending laws or verifiable identity theft are written off at the time of repurchase or at the time an indemnification payment is made. The maximum potential amount of future payments associated under this obligation is the outstanding balances of the Borrower Loans issued through the Whole Loan Channel, which at September 30, 2019 is $3.8 billion . Pros per has accrued $1.0 million and $0.9 million as of September 30, 2019 and December 31, 2018, respectively, in regard to this obligation. Regulatory Contingencies Prosper accrues for contingencies when a loss from such contingencies is probable and the amount of loss can be reasonably estimated. In determining whether a loss is probable and if it is possible to quantify the amount of the estimated loss, Prosper reviews and evaluates its litigation and regulatory matters on at least a quarterly basis in light of potentially relevant factual and legal developments. If Prosper determines that an unfavorable outcome is not probable or that the amount of a loss cannot be reasonably estimated, Prosper does not accrue for a potential litigation loss. If an unfavorable outcome is probable and Prosper can estimate a range of outcomes, we record the amount we consider to be the best estimate within the range of potential losses that are both probable and estimable; however, if we cannot quantify the amount of the estimated loss, then we record the low end of the range of those potential losses. SEC Inquiry In April 2017, we became aware of an error in the annualized net return and seasoned annualized net return numbers displayed to Note investors. Prosper was advised by the SEC that it was investigating whether violations of federal securities laws had occurred in connection with the error. On April 19, 2019, the SEC accepted an offer of settlement from PFL to resolve the matter. Under the settlement, the SEC alleged a violation of Section 17(a)(2) of the Securities Act and ordered PFL to cease and desist from any future violations of that provision. PFL neither admitted nor denied any wrongdoing, and agreed to pay a civil monetary penalty of $3.0 million. The SEC credited PFL’s prompt remedial acts in response to the error and Prosper's cooperation with the SEC staff during the investigation. The penalty of $3.0 million was paid in full in April 2019.
Prosper Funding LLC
Entity Information [Line Items]
Commitments and Contingencies	Commitments and Contingencies Operating Commitments Prosper entered into an agreement with WebBank, under which all Borrower Loans originated through the marketplace are made by WebBank under its bank charter. Pursuant to the agreement, the marketing fee that Prosper receives in connection with the origination of each loan is partially reduced by an amount (the “Designated Amount”) calculated as a percentage of the principal amount of such loan based on the aggregate principal amount of loans originated for the applicable month. To the extent the aggregate Designated Amount for all loans originated during any month is less than $143,500, Prosper is required to pay WebBank an amount equal to such deficiency. Accordingly, the minimum fee for the remaining three months of 2019 is $0.4 million . The minimum fee is $1.7 million for the years 2020 and 2021, and the minimum fee is $0.1 million for the year 2022. Additionally, under the agreement with WebBank, Prosper is required to maintain minimum net liquidity of $15 million at all times during the term of the agreement. Net liquidity is defined as the sum of Cash, Cash Equivalents and Available for Sale Investments. Violation of this covenant can result in termination of the contract with WebBank. As of September 30, 2019, we were in compliance with the covenant. Loan Purchase Commitments Under the terms of Prosper Funding’s agreement with WebBank, Prosper Funding is committed to purchase $33.4 million of Borrower Loans that WebBank originated during the last two business days of the quarter ended September 30, 2019 and first business day of the quarter ending December 31, 2019. Prosper Funding will purchase these Borrower Loans within the first three business days of the quarter ending December 31, 2019. Repurchase and Indemnification Contingency Under the terms of the loan purchase agreements between Prosper Funding and investors that participate in the Whole Loan Channel, Prosper Funding may, in certain circumstances, become obligated to repurchase a Borrower Loan from an investor. Generally, these circumstances include the occurrence of verifiable identity theft, the failure to properly follow loan listing or bidding protocols, or a violation of the applicable federal, state, or local lending laws. The fair value of the indemnification and repurchase obligation is estimated based on historical experience. Prosper Funding recognizes a liability for the repurchase and indemnification obligation when the Borrower Loans are issued. Indemnified or repurchased Borrower Loans associated with violations of federal, state, or local lending laws or verifiable identity theft are written off at the time of repurchase or at the time an indemnification payment is made. The maximum potential amount of future payments associated under this obligation is the outstanding balances of the Borrower Loans issued through the Whole Loan Channel, which as of September 30, 2019 is $3.8 billion. P rosper Funding had acc rued $1.0 million and $0.9 million as of September 30, 2019 and December 31, 2018, respectively, in regard to this obligation. Regulatory Contingencies Prosper accrues for contingencies when a loss from such contingencies is probable and the amount of loss can be reasonably estimated. In determining whether a loss is probable and if it is possible to quantify the amount of the estimated loss, Prosper reviews and evaluates its litigation and regulatory matters on at least a quarterly basis in light of potentially relevant factual and legal developments. If Prosper determines that an unfavorable outcome is not probable or that the amount of a loss cannot be reasonably estimated, Prosper does not accrue for a potential litigation loss. If an unfavorable outcome is probable and Prosper can estimate a range of outcomes, we record the amount we consider to be the best estimate within the range of potential losses that are both probable and estimable; however, if we cannot quantify the amount of the estimated loss, then we record the low end of the range of those potential losses. SEC Inquiry In April 2017, we became aware of an error in the annualized net return and seasoned annualized net return numbers displayed to Note investors. Prosper was advised by the SEC that it was investigating whether violations of federal securities laws had occurred in connection with the error. On April 19, 2019, the SEC accepted an offer of settlement from PFL to resolve the matter. Under the settlement, the SEC alleged a violation of Section 17(a)(2) of the Securities Act and ordered PFL to cease and desist from any future violations of that provision. PFL neither admitted nor denied any wrongdoing, and agreed to pay a civil monetary penalty of $3.0 million. The SEC credited PFL’s prompt remedial acts in response to the error and Prosper’s cooperation with the SEC staff during the investigation. The penalty of $3.0 million was paid in full in April 2019.

Related Parties

Related Parties	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Related Parties	Related Parties Since Prosper’s inception, it has engaged in various transactions with its directors, executive officers, and holders of more than 10% of its voting securities, and immediate family members and other affiliates of its directors, executive officers, and 10% stockholders. Prosper believes that all of the transactions described below were made on terms no less favorable to Prosper than could have been obtained from unaffiliated third parties. Prosper’s executive officers, directors who are not executive officers, and certain affiliates participate in its marketplace by placing bids and purchasing Notes and Borrower Loans. The aggregate amount of the Notes and Borrower Loans purchased and the income earned by parties deemed to be affiliates and related parties of Prosper for the three and nine months ended September 30, 2019 and September 30, 2018, as well as the Notes and Borrower Loans outstanding as of September 30, 2019 and December 31, 2018 are summarized below (in thousands): Aggregate Amount of Interest Earned on Related Party 2019 2018 2019 2018 Executive officers and management $ 6 $ 3 $ 1 $ — Directors (excluding executive officers and management) 101 107 13 11 Total $ 107 $ 110 $ 14 $ 11 Aggregate Amount of Notes and Borrower Loans Purchased Nine Months Ended September 30, Interest Earned on Notes and Borrower Loans Nine Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 17 $ 12 $ 4 $ 1 Directors (excluding executive officers and management) 309 315 37 33 Total $ 326 $ 327 $ 41 $ 34 Notes Balance as of Related Party September 30, 2019 December 31, 2018 Executive officers and management $ 35 $ 32 Directors (excluding executive officers and management) 618 569 $ 653 $ 601
Prosper Funding LLC
Entity Information [Line Items]
Related Parties	Related Parties Since inception, Prosper Funding has engaged in various transactions with its directors, executive officers, and sole member, and immediate family members and other affiliates of its directors, executive officers, and sole member. Prosper Funding believes that all of the transactions described below were made on terms no less favorable to Prosper Funding than could have been obtained from unaffiliated third parties. Prosper Funding’s executive officers and directors who are not executive officers participate in its marketplace by placing bids and purchasing Notes and Borrower Loans. The aggregate amount of the Notes and Borrower Loans purchased and the income earned by parties deemed to be related parties of Prosper Funding as of September 30, 2019 and December 31, 2018 are summarized below (in thousands): Aggregate Amount of Notes and Borrower Loans Purchased Interest Earned on Three Months Ended September 30, Three Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 6 $ 3 $ 1 $ — Directors (excluding executive officers and management) — — — — Total $ 6 $ 3 $ 1 $ — Aggregate Amount of Notes and Borrower Loans Purchased Interest Earned on Nine Months Ended September 30, Nine Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 17 $ 12 $ 4 $ 1 Directors (excluding executive officers and management) — — — — Total $ 17 $ 12 $ 4 $ 1 Note and Borrower Loan Balance as of Related Party September 30, 2019 December 31, 2018 Executive officers and management $ 35 $ 32 Directors (excluding executive officers and management) — — $ 35 $ 32

Significant Concentrations

Significant Concentrations	9 Months Ended
	Sep. 30, 2019
Risks and Uncertainties [Abstract]
Significant Concentrations	Significant Concentrations Prosper is dependent on third party funding sources such as banks, asset managers, and investment funds to provide the funds to allow WebBank to originate Borrower Loans that the third party funding sources will later purchase. Of all Borrower Loans originated in the nine months ended September 30, 2019, one party purchased 11% of such loans. This compares to 52% for the largest purchasing party for the nine months ended September 30, 2018. Further, a significant portion of our business is dependent on funding through the Whole Loan Channel, through which 93% and 93% of Borrower Loans were originated in the nine months ended September 30, 2019 and September 30, 2018, respectively.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Basis of Presentation	Basis of Presentation Prosper Marketplace, Inc. (“PMI”) was incorporated in the state of Delaware on March 22, 2005. Except as the context requires otherwise, as used in these notes to the condensed consolidated financial statements of PMI, “Prosper,” “we,” “us,” and “our” refer to PMI and its wholly-owned subsidiaries, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018. The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. The preparation of Prosper’s condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in Prosper’s financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions. The accompanying interim condensed consolidated financial statements include the accounts of PMI, its wholly-owned subsidiaries and consolidated variable interest entities ("VIEs"). All intercompany balances have been eliminated in consolidation. Securitization Notes are notes held by certain third party investors pursuant to Prosper’s securitization transactions, and are distinguishable from the borrower payment dependent Notes available to investors through our Note Channel.
Fair Value Measurements	Fair Value Measurements Financial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Available for Sale Investments at Fair Value, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors, Convertible Preferred Stock Warrant Liability, Certificates Issued by Securitization Trust and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short term nature.
Restricted Cash	Restricted Cash Restricted Cash consists primarily of cash deposits and short term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors or Prosper have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor.
Borrower Loans, Loans Held for Sale and Notes	Borrower Loans, Loans Held for Sale and NotesThrough the Note Channel, Prosper purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes issued through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans funded and Notes issued through the Note Channel are carried on Prosper’s condensed consolidated balance sheets as assets and liabilities, respectively. We choose to measure certain financial instruments and certain other items at fair value on an instrument-by-instrument basis with unrealized gains and losses on items for which the fair value option has been elected reported in earnings. Management believes that the fair value option is more meaningful for the readers of the financial statements and it allows both the Borrower Loans and Notes to be valued using the same methodology. The fair value election, with respect to an item, may not be revoked once an election is made. Prosper estimates the fair value of such Borrower Loans and Notes using discounted cash flow methodologies that take into account expected prepayments, losses, recoveries and default rates. The Borrower Loans are not derecognized when a corresponding Note is issued as Prosper maintains the ability to sell the Borrower Loans without the approval of the holders of the corresponding Notes.
Leases	Leases We determine if an arrangement is a lease at inception. Operating lease right-of-use (“ROU”) assets and operating lease liabilities are included on our condensed consolidated balance sheets in the Property and Equipment, Net and the Other Liabilities sections, respectively. If a contract contains a lease, we evaluate whether it should be classified as an operating or finance lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For certain leases with original terms of twelve months or less we recognize the lease expense as incurred and we do not recognize ROU assets and lease liabilities.
Consolidation of Variable Interest Entities	Consolidation of Variable Interest Entities The determination of whether to consolidate a variable interest entity (“VIE”) in which we have a variable interest requires a significant amount of analysis and judgment regarding whether we are the primary beneficiary of a VIE due to our holding a controlling financial interest in the VIE. A controlling financial interest in a VIE exists if we have both the power to direct the VIE’s activities that most significantly affect the VIE’s economic performance and a potentially significant economic interest in the VIE. The determination of whether an entity is a VIE considers factors, such as (i) whether the entity’s equity investment at risk is insufficient to allow the entity to finance its activities without additional subordinated financial support and (ii) whether a holder’s equity investment at risk lacks any of the following characteristics of a controlling financial interest: the direct or indirect ability through voting rights or similar rights to make decisions about a legal entity’s activities that have a significant effect on the entity’s success, the obligation to absorb the expected losses of the entity or the right to receive the expected residual returns of the legal entity. Management regularly reviews and reconsiders its previous conclusions regarding the status of an entity as a VIE and whether we are required to consolidate such VIE in the consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period In June 2018, the FASB issued ASU No. 2018-07, "Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting." The ASU is intended to reduce the cost and complexity and to improve financial reporting for nonemployee share-based payments. The ASU expands the scope of Topic 718, Compensation-Stock Compensation, which currently only includes share-based payments to employees, to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. Prosper adopted the standard effective January 1, 2019. The adoption of this standard did not have a material impact on Prosper’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)," which requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases, along with additional qualitative and quantitative disclosures. Prosper adopted the standard effective January 1, 2019. In accordance with ASU 2018-11, "Leases (Topic 842), Target Improvements", Prosper has elected not to restate prior periods and has presented the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings on January 1, 2019. The standard had a material impact on our consolidated balance sheets, but did not materially impact our consolidated statement of operations. The most significant impact is the recognition of ROU assets and lease obligation liabilities for operating leases. Additionally, Prosper recorded an impairment charge to its ROU asset upon adoption due to existing sublease arrangements that were entered into at a loss. The impairment charge did not have a material impact as it will be offset by a reduction of the existing restructuring liability for those leases. Prosper has elected the package of practical expedients, which allows us not to reassess (1) whether any expired or existing contracts as of the adoption date are or contain a lease, (2) lease classification for any expired or existing leases as of the adoption date and (3) initial direct costs for any existing leases as of the adoption date. We did not elect to apply the hindsight practical expedient when determining lease term and assessing impairment of right-of-use assets. We also elected a practical expedient that allowed us to not separate non-lease components from lease components and instead to account for each lease and non-lease component as a single lease component. The adoption of ASU 2016-02 on January 1, 2019 resulted in the recognition of ROU assets of approximately $16.1 million, lease liabilities for operating leases of approximately $21.6 million, a reduction in existing other liabilities of $5.1 million related to deferred rent and restructuring liabilities, and no cumulative-effect adjustment on retained earnings on Prosper's Consolidated Balance Sheets, with no material impact to its Consolidated Statements of Operations. Accounting Standards Issued, To Be Adopted By Prosper In Future Periods In June 2016, the FASB amended guidance related to impairment of financial instruments as part of ASU 2016-13, "Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments", which will be effective for interim and annual periods beginning after December 15, 2019. For loans accounted for at amortized cost, the guidance replaces the incurred loss impairment methodology with an expected credit loss model for which a company recognizes an allowance based on the estimate of expected credit loss. Because Prosper accounts for Borrower Loans at fair value through net income, Prosper expects no impact on its loan portfolios upon adoption. For certain available for sale investments, the guidance will require recognition of expected credit losses through recording an allowance for credit losses. The recognition of this allowance is limited to the difference between the security’s amortized cost basis and fair value. Prosper does not expect the targeted amendments to the available for sale debt securities impairment model to have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment." The standard eliminates Step 2 from the goodwill impairment test, which requires a hypothetical purchase price allocation. Prosper will continue to have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The standard is effective for interim and annual periods beginning after December 15, 2019 and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The standard should be applied on a prospective basis. Prosper does not expect the adoption of this guidance to impact its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement." Entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but public companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU No. 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, but entities are permitted to early adopt either the entire standard or only the provisions that eliminate or modify the requirements. The guidance only affects disclosures in the notes to the consolidated financial statements and will not affect Prosper’s balance sheet or statements of operations. In August 2018, the FASB issued ASU No. 2018-15, "Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract." This ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year and early adoption is permitted. Prosper will prospectively capitalize all eligible costs related to cloud computing arrangements starting January 1, 2020. In March 2019, the FASB issued ASU No. 2019-01, "Leases (Topic 842): Codification Improvements." This ASU aligns the fair value treatment of the underlying asset by lessors that are not manufacturers or dealers as defined under Topic 842, presentation on the Statement of Cash Flows for sales and direct financing leases, and a clarification of interim disclosure requirements in the year of adoption, among other things. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year and early adoption is permitted. Prosper is currently evaluating the impact of this accounting standard update on its consolidated financial statements.
Prosper Funding LLC
Entity Information [Line Items]
Basis of Presentation	Basis of Presentation Prosper Funding LLC (“PFL”) was formed in the state of Delaware on February 17, 2012 as a limited liability company with the sole equity member being Prosper Marketplace, Inc. (“PMI”). Except as the context otherwise requires, as used in these Notes to the condensed consolidated financial statements of Prosper Funding LLC, “Prosper Funding,” “we,” “us,” and “our” refers to PFL and its wholly owned subsidiaries, Prosper Asset Holdings LLC (“PAH”), a Delaware limited liability company, and Prosper Depositor LLC, a Delaware limited liability company, on a consolidated basis. PAH was dissolved on November 28, 2018. As a result, references to Prosper Funding do not include PAH for periods subsequent to the year ended December 31, 2018. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018. The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. Prosper Funding did not have any items of other comprehensive income (loss) during any of the periods presented in the condensed consolidated financial statements as of and for the nine months ended September 30, 2019 and September 30, 2018. The preparation of Prosper Funding's condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in its condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions, and the differences could be material.
Fair Value Measurements	Fair Value MeasurementsFinancial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Short Term Investments, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short term nature.
Restricted Cash	Restricted Cash Restricted cash consists primarily of cash deposits and short term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors or Prosper has on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor.
Borrower Loans, Loans Held for Sale and Notes	Borrower Loans, Loans Held for Sale and NotesThrough the Note Channel, Prosper Funding purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes funded through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans and Notes funded through the Note Channel are carried on Prosper Funding’s condensed consolidated balance sheets as assets and liabilities, respectively. We choose to measure certain financial instruments and certain other items at fair value on an instrument-by-instrument basis with unrealized gains and losses on items for which the fair value option has been elected reported in earnings. Management believes that the fair value option is more meaningful for the readers of the financial statements and it allows both the Borrower Loans and Notes to be valued using the same methodology. The fair value election, with respect to an item, may not be revoked once an election is made. Prosper Funding estimates the fair value of such Borrower Loans and Notes using discounted cash flow methodologies that take into account expected prepayments, losses, recoveries and default rates. The Borrower Loans are not derecognized when a corresponding Note is issued as Prosper Funding maintains the ability to sell the Borrower Loans without the approval of the holders of the corresponding Notes.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period No accounting standards were adopted in the current period for Prosper Funding LLC. Accounting Standards Issued, To Be Adopted By Prosper Funding In Future Periods In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement." Entities will no longer be required to disclose the amount of and reasons for transfers between level 1 and level 2 of the fair value hierarchy, but public companies will be required to disclose the range and weighted average used to develop significant unobservable inputs for level 3 fair value measurements. ASU No. 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, but entities are permitted to early adopt either the entire standard or only the provisions that eliminate or modify the requirements. The guidance only affects disclosures in the notes to the consolidated financial statements and will not affect Prosper’s balance sheet or statements of operations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of Cash, Cash Equivalents, and Restricted Cash reported within the condensed consolidated balance sheets that sum to the total of the same such amount shown in the condensed consolidated statements of cash flows: September 30, 2019 December 31, 2018 September 30, 2018 December 31, 2017 Cash and Cash Equivalents $ 55,300 $ 57,945 $ 58,447 $ 45,795 Restricted Cash 158,302 149,114 145,233 152,668 Total Cash, Cash Equivalents and Restricted Cash shown in the consolidated statements of cash flows $ 213,602 $ 207,059 $ 203,680 $ 198,463
Prosper Funding LLC
Entity Information [Line Items]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amount shown in the condensed consolidated statements of cash flows: September 30, 2019 December 31, 2018 September 30, 2018 December 31, 2017 Cash and Cash Equivalents $ 13,716 $ 11,163 $ 9,643 $ 8,223 Restricted Cash 125,442 136,018 132,573 140,092 Total Cash, Cash Equivalents and Restricted Cash show in the condensed consolidated statements of cash flows $ 139,158 $ 147,181 $ 142,216 $ 148,315

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Property and Equipment, Net	Property and equipment consist of the following (in thousands): September 30, 2019 December 31, 2018 Property and Equipment: Operating lease right-of-use assets $ 16,138 $ — Computer equipment 12,797 15,193 Internal-use software and website development costs 24,783 22,505 Office equipment and furniture 2,999 3,015 Leasehold improvements 7,158 7,157 Assets not yet placed in service 4,647 2,745 Property and equipment 68,522 50,615 Less accumulated depreciation and amortization (37,223) (35,342) Total Property and Equipment, Net $ 31,299 $ 15,273
Prosper Funding LLC
Entity Information [Line Items]
Property and Equipment, Net	Property and equipment consist of the following (in thousands): September 30, 2019 December 31, 2018 Property and equipment: Internal-use software and web site development costs $ 21,558 $ 22,505 Less accumulated depreciation and amortization (16,626) (16,079) Total property and equipment, net $ 4,932 $ 6,426

Borrower Loans, Loans Held fo_2

Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale	The aggregate principal balances outstanding and fair values of Borrower Loans, Loans Held for Sale, and Notes as of September 30, 2019 and December 31, 2018, are presented in the following table (in thousands): Borrower Loans Notes Loans Held for Sale September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Aggregate principal balance outstanding $ 554,208 $ 269,093 $ (254,369) $ (272,430) $ 231,678 $ 185,657 Fair value adjustments (13,239) (5,571) 6,644 8,427 (34) (1,869) Fair value $ 540,969 $ 263,522 $ (247,725) $ (264,003) $ 231,644 $ 183,788
Prosper Funding LLC
Entity Information [Line Items]
Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale	The aggregate principal balances outstanding and fair values of Borrower Loans and Notes as of September 30, 2019 and December 31, 2018, are presented in the following table (in thousands): Borrower Loans Notes September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Aggregate principal balance outstanding $ 251,796 $ 269,093 $ (254,369) $ (272,430) Fair value adjustments (4,078) (5,571) 6,644 8,427 Fair value $ 247,718 $ 263,522 $ (247,725) $ (264,003)

Available for Sale Investment_2

Available for Sale Investments, at Fair Value (Tables)	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Securities Available for Sale	The amortized cost, gross unrealized gains and losses, and fair value of available for sale investments as of September 30, 2019 and December 31, 2018, are as follows (in thousands): September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturity securities: Treasury Bills $ — $ — $ — $ — US Treasury securities 1,500 — — 1,500 Total Available for Sale Investments $ 1,500 $ — $ — $ 1,500 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturity securities: Treasury Bills $ 17,940 $ — $ (3) $ 17,937 US Treasury securities 4,246 — (10) 4,236 Total Available for Sale Investments $ 22,186 $ — $ (13) $ 22,173
Summary of Securities Available for Sale of Continuous Unrealized Loss	A summary of available for sale investments with unrealized losses as of December 31, 2018, aggregated by category and period of continuous unrealized loss, is as follows (in thousands): Less than 12 months 12 months or longer Total December 31, 2018 Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Fixed maturity securities: Treasury Bills $ 17,937 $ (3) $ — $ — $ 17,937 $ (3) US Treasury securities — — 4,236 (10) 4,236 (10) Total Investments with Unrealized Losses $ 17,937 $ (3) $ 4,236 $ (10) $ 22,173 $ (13)
Schedule of Maturities of Securities Available for Sale	The maturities of available for sale investments at September 30, 2019 and December 31, 2018 are as follows (in thousands): September 30, 2019 Within 1 year After 1 year through 5 years After 5 years to 10 years After 10 years Total Treasury Bills $ — $ — $ — $ — $ — US Treasury securities 1,500 — — — 1,500 Total Fair Value $ 1,500 $ — $ — $ — $ 1,500 Total Amortized Cost $ 1,500 $ — $ — $ — $ 1,500 December 31, 2018 Within 1 year After 1 year through 5 years After 5 years to 10 years After 10 years Total Treasury Bills $ 17,937 $ — $ — $ — $ 17,937 US Treasury securities 4,236 — — — 4,236 Total Fair Value $ 22,173 $ — $ — $ — $ 22,173 Total Amortized Cost $ 22,186 $ — $ — $ — $ 22,186

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2019 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 540,969 $ 540,969 Loans Held for Sale — — 231,644 231,644 Available for Sale Investments, at Fair Value — 1,500 — 1,500 Servicing Assets — — 12,936 12,936 Total Assets $ — $ 1,500 $ 785,549 $ 787,049 Liabilities: Notes $ — $ — $ 247,725 $ 247,725 Servicing Liabilities — — 2 2 Certificates Issued by Securitization Trust, at Fair Value — — 37,564 37,564 Convertible Preferred Stock Warrant Liability — — 152,342 152,342 Loan Trailing Fee Liability — — 3,281 3,281 Total Liabilities $ — $ — $ 440,914 $ 440,914 December 31, 2018 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 263,522 $ 263,522 Loans Held for Sale — — 183,788 183,788 Available for Sale Investments, at Fair Value — 22,173 — 22,173 Servicing Assets — — 14,687 14,687 Total Assets $ — $ 22,173 $ 461,997 $ 484,170 Liabilities: Notes $ — $ — $ 264,003 $ 264,003 Servicing Liabilities — — 12 12 Convertible Preferred Stock Warrant Liability — — 143,679 143,679 Loan Trailing Fee Liability — — 3,118 3,118 Total Liabilities $ — $ — $ 410,812 $ 410,812
Quantitative Information About Significant Unobservable Inputs	Borrower Loans, Loans Held for Sale and Notes: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 4.7% - 12.3% 4.7% - 13.8% Default rate 2.1% - 18.4% 2.0% - 15.8%
Significant Unobservable Inputs Fair Value	Servicing Rights: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% Market servicing rate 0.625 % 0.625 % Loan Trailing Fee Liability: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1%
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present additional information about level 3 Borrower Loans, Loans Held for Sale and Notes measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Certificates Issued by Securitization Trust Loans Held for Sale Total Balance at July 1, 2019 $ 606,799 $ (253,425) $ (44,090) $ 114,962 $ 424,246 Purchase of Borrower Loans/Issuance of Notes 41,460 (41,439) — 647,896 647,917 Principal repayments (87,348) 40,993 4,173 (19,580) (61,762) Borrower Loans sold to third parties (1,526) — — (511,596) (513,122) Other changes 240 (65) 252 832 1,259 Change in fair value (18,656) 6,211 2,101 (870) (11,214) Balance at September 30, 2019 $ 540,969 $ (247,725) $ (37,564) $ 231,644 $ 487,324 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2018 $ 277,361 $ (277,425) $ 116,817 $ 116,753 Purchase of Borrower Loans/Issuance of Notes 43,596 (43,797) 542,910 542,709 Principal repayments (42,139) 43,418 (13,105) (11,826) Borrower Loans sold to third parties (843) — (530,496) (531,339) Other changes 24 (9) 73 88 Change in fair value (9,450) 9,225 (3,004) (3,229) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 113,195 $ 113,156 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Certificates Issued by Securitization Trust Loans Held for Sale Total Balance at January 1, 2019 $ 263,522 $ (264,003) $ — $ 183,788 $ 183,307 Purchase of Borrower Loans/Issuance of Notes 390,089 (128,152) (51,595) 1,809,133 2,019,475 Transfers in (Transfers out) 147,773 — — (147,773) — Principal repayments (221,379) 126,721 8,445 (46,109) (132,322) Borrower Loans sold to third parties (3,412) — — (1,564,904) (1,568,316) Other changes 331 538 (351) 921 1,439 Change in fair value (35,955) 17,171 5,937 (3,412) (16,259) Balance at September 30, 2019 $ 540,969 $ (247,725) $ (37,564) $ 231,644 $ 487,324 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2018 $ 293,005 $ (293,948) $ 49 $ (894) Purchase of Borrower Loans/Issuance of Notes 134,671 (134,490) 1,867,010 1,867,191 Principal repayments (131,086) 134,943 (27,370) (23,513) Borrower Loans sold to third parties (2,859) — (1,724,147) (1,727,006) Other changes (314) 624 869 1,179 Change in fair value (24,868) 24,283 (3,216) (3,801) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 113,195 $ 113,156
Schedule of Servicing Assets and Liabilities Measured at Fair Value	The following tables present additional information about level 3 servicing assets measured at fair value on a recurring basis (in thousands): Servicing Fair Value at July 1, 2019 $ 13,387 Additions 2,859 Less: Changes in fair value (3,310) Fair Value at September 30, 2019 $ 12,936 Servicing Fair Value at July 1, 2018 15,644 Additions 3,156 Less: Changes in fair value (3,362) Fair Value at September 30, 2018 $ 15,438 Servicing Assets Fair Value at January 1, 2019 $ 14,687 Additions 9,237 Derecognition (1,049) Less: Changes in fair value (9,939) Fair Value at September 30, 2019 $ 12,936 Servicing Assets Fair Value at January 1, 2018 $ 14,711 Additions 10,658 Derecognition — Less: Changes in fair value (9,931) Fair Value at September 30, 2018 $ 15,438 The following table presents additional information about level 3 Preferred Stock Warrant Liability measured at fair value on a recurring basis (in thousands): Preferred Stock Balance as of July 1, 2019 $ 166,559 Add Issuances of Preferred Stock Warrant — Change in Fair Value of the Preferred Stock Warrant Liability (14,217) Balance as of September 30, 2019 $ 152,342 Preferred Stock Balance as of July 1, 2018 $ 143,676 Add Issuances of Preferred Stock Warrant 19,561 Change in Fair Value of the Preferred Stock Warrant Liability (9,283) Balance as of September 30, 2018 $ 153,954 Preferred Stock Balance as of January 1, 2019 $ 143,679 Add Issuances of Preferred Stock Warrant 17,553 Change in Fair Value of the Preferred Stock Warrant Liability (8,890) Balance as of September 30, 2019 $ 152,342 Preferred Stock Balance as of January 1, 2018 $ 116,366 Add Issuances of Preferred Stock Warrant 55,473 Change in Fair Value of the Preferred Stock Warrant Liability (17,885) Balance as of September 30, 2018 $ 153,954 Loan Trailing Fee The fair value of the Loan Trailing Fee represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and defaults rates using a discounted cash flow model. The following table presents additional information about level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Balance at January 1, 2019 $ 3,118 Issuances 2,063 Cash Payment of Loan Trailing Fee (1,744) Change in Fair Value (156) Balance at September 30, 2019 $ 3,281
Fair Value Assumptions for Loans Held for Sale, Borrower Loans and Notes	Key economic assumptions and the sensitivity of the current fair value to immediate changes in those assumptions at September 30, 2019 for Borrower Loans, Loans Held for Sale and Notes funded through the Note Channel are presented in the following table (in thousands, except percentages): Borrower Loans and Loans Held for Sale Notes Fair Value as of September 30, 2019 $ 772,613 $ 247,725 Discount rate assumption: 7.03 % * 6.90 % * Resulting fair value from: 100 basis point increase $ 765,521 $ 245,448 200 basis point increase $ 758,597 $ 243,225 Resulting fair value from: 100 basis point decrease $ 779,880 $ 250,059 200 basis point decrease $ 787,326 $ 252,450 Default rate assumption: 12.27 % * 13.50 % * Resulting fair value from: 100 basis point increase $ 762,459 $ 244,453 200 basis point increase $ 752,608 $ 241,278 Resulting fair value from: 100 basis point decrease $ 782,961 $ 251,059 200 basis point decrease $ 793,379 $ 254,417 * Represents weighted average assumptions considering all credit grades.
Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities	The following table presents the estimated impact on Prosper’s estimated fair value of servicing assets, calculated using different market servicing rates and different default rates as of September 30, 2019 (in thousands, except percentages). Servicing Assets Fair Value as of September 30, 2019 $ 12,936 Market servicing rate assumptions 0.625 % Resulting fair value from: Market servicing rate increase to 0.65% $ 12,148 Market servicing rate decrease to 0.60% $ 13,758 Weighted average prepayment assumptions 21.49 % Resulting fair value from: Applying a 1.1 multiplier to prepayment rate $ 12,781 Applying a 0.9 multiplier to prepayment rate $ 13,127 Weighted average default assumptions 12.70 % Resulting fair value from: Applying a 1.1 multiplier to default rate $ 12,793 Applying a 0.9 multiplier to default rate $ 13,116
Financial Instruments, Assets And Liabilities Not Recorded At Fair Value	The following table presents the fair value hierarchy for financial instruments, assets, and liabilities not recorded at fair value (in thousands): September 30, 2019 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 55,300 $ 55,300 $ — $ — $ 55,300 Restricted Cash 158,302 — 158,302 — 158,302 Accounts Receivable 1,670 — 1,670 — 1,670 Total Assets $ 215,272 $ 55,300 $ 159,972 $ — $ 215,272 Liabilities: Accounts Payable and Accrued Liabilities $ 20,305 $ — $ 20,305 $ — $ 20,305 Payable to Investors 113,507 — 113,507 — 113,507 Notes Issued by Securitization Trust 260,060 — 265,207 — 265,207 Warehouse Lines 205,818 — 205,818 — 205,818 Total Liabilities $ 599,690 $ — $ 604,837 $ — $ 604,837 December 31, 2018 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 57,945 $ 57,945 $ — $ — $ 57,945 Restricted Cash 149,114 — 149,114 — 149,114 Accounts Receivable 5,119 — 5,119 — 5,119 Total Assets $ 212,178 $ 57,945 $ 154,233 $ — $ 212,178 Liabilities: Accounts Payable and Accrued Liabilities $ 19,967 $ — $ 19,967 $ — $ 19,967 Payable to Investors 127,538 — 127,538 — 127,538 Warehouse Lines 162,488 — 162,488 — 162,488 Total Liabilities $ 309,993 $ — $ 309,993 $ — $ 309,993
Prosper Funding LLC
Entity Information [Line Items]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2019 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 247,718 $ 247,718 Servicing Assets — — 15,220 15,220 Total Assets $ — $ — $ 262,938 $ 262,938 Liabilities: Notes $ — $ — $ 247,725 $ 247,725 Servicing Liabilities — — 2 2 Loan Trailing Fee Liability — — 3,281 3,281 Total Liabilities $ — $ — $ 251,008 $ 251,008 December 31, 2018 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans $ — $ — $ 263,522 $ 263,522 Servicing Assets — — 15,550 15,550 Total Assets $ — $ — $ 279,072 $ 279,072 Liabilities: Notes $ — $ — $ 264,003 $ 264,003 Servicing Liabilities — — 12 12 Loan Trailing Fee Liability — — 3,118 3,118 Total Liabilities $ — $ — $ 267,133 $ 267,133
Quantitative Information About Significant Unobservable Inputs	The following tables present quantitative information about the significant unobservable inputs used for Prosper Funding’s level 3 fair value measurements at September 30, 2019 and December 31, 2018: Borrower Loans and Notes: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 4.7% - 12.2% 4.7% - 13.8% Default rate 2.3% - 17.7% 2.0% - 15.8%
Significant Unobservable Inputs Fair Value	Servicing Assets and Liabilities: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1% Market servicing rate 0.625 % 0.625 % Loan Trailing Fee Liability: Range Unobservable Input September 30, 2019 December 31, 2018 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.8% - 18.8% 1.6% - 16.7% Prepayment rate 16.5% - 27.8% 15.5% - 25.1%
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The changes in the Borrower Loans, Loans Held for Sale and Notes, which are level 3 assets and liabilities measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2019 $ 254,070 $ (253,425) $ — $ 645 Originations 41,460 (41,439) 647,896 647,917 Principal repayments (40,600) 40,993 — 393 Borrower Loans sold to third parties (855) — (647,896) (648,751) Other changes (26) (65) — (91) Change in fair value (6,331) 6,211 — (120) Balance at September 30, 2019 $ 247,718 $ (247,725) $ — $ (7) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at July 1, 2018 $ 277,361 $ (277,425) $ 31 $ (33) Originations 43,596 (43,797) 542,910 542,709 Principal repayments (42,139) 43,418 (6) 1,273 Borrower Loans sold to third parties (843) — (542,899) (543,742) Other changes 24 (9) — 15 Change in fair value (9,450) 9,225 (25) (250) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 11 $ (28) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2019 $ 263,522 $ (264,003) $ — $ (481) Originations 127,522 (128,152) 1,809,133 1,808,503 Principal repayments (123,014) 126,721 — 3,707 Borrower Loans sold to third parties (2,578) — (1,809,133) (1,811,711) Other changes (226) 538 — 312 Change in fair value (17,508) 17,171 — (337) Balance at September 30, 2019 $ 247,718 $ (247,725) $ — $ (7) Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Borrower Loans Notes Loans Held for Sale Total Balance at January 1, 2018 $ 293,005 $ (293,948) $ 49 $ (894) Originations 134,671 (134,490) 1,867,010 1,867,191 Principal repayments (131,086) 134,943 (20) 3,837 Borrower Loans sold to third parties (2,859) — (1,866,999) (1,869,858) Other changes (314) 624 — 310 Change in fair value (24,868) 24,283 (29) (614) Balance at September 30, 2018 $ 268,549 $ (268,588) $ 11 $ (28)
Schedule of Servicing Assets and Liabilities Measured at Fair Value	The following table presents additional information about level 3 servicing assets recorded at fair value (in thousands): Servicing Assets Fair Value at July 1, 2019 $ 15,461 Additions 3,436 Less: Changes in fair value (3,677) Fair Value at September 30, 2019 $ 15,220 Servicing Assets Fair Value at July 1, 2018 $ 16,162 Additions 3,198 Less: Changes in fair value (3,430) Fair Value at September 30, 2018 $ 15,930 Servicing Assets Fair Value at January 1, 2019 $ 15,550 Additions 10,232 Less: Changes in fair value (10,562) Fair Value at September 30, 2019 $ 15,220 Servicing Assets Fair Value at January 1, 2018 $ 14,598 Additions 11,345 Less: Changes in fair value (10,013) Fair Value at September 30, 2018 $ 15,930 Loan Trailing Fee The fair value of the Loan Trailing Fee represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and defaults rates using a discounted cash flow model. The following table presents additional information about level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Liability Fair Value at January 1, 2019 $ 3,118 Issuances 2,063 Cash payment of Loan Trailing Fee (1,744) Change in fair value (156) Fair Value at September 30, 2019 $ 3,281
Fair Value Assumptions for Loans Held for Sale, Borrower Loans and Notes	Key economic assumptions and the sensitivity of the current fair value to immediate changes in those assumptions at September 30, 2019 for Borrower Loans, Loans Held for Sale and Notes funded are presented in the following table (in thousands, except percentages): Borrower Loans Notes Fair Value at September 30, 2019 $ 247,718 $ 247,725 Discount rate assumption: 6.90 % * 6.90 % * Resulting fair value from: 100 basis point increase $ 245,444 $ 245,448 200 basis point increase $ 243,224 $ 243,225 Resulting fair value from: 100 basis point decrease $ 250,048 $ 250,059 200 basis point decrease $ 252,435 $ 252,450 Default rate assumption: 13.50 % * 13.50 % * Resulting fair value from: 100 basis point increase $ 244,463 $ 244,453 200 basis point increase $ 241,304 $ 241,278 Resulting fair value from: 100 basis point decrease $ 251,036 $ 251,059 200 basis point decrease $ 254,376 $ 254,417 * Represe nts weighted average assumptions considering all credit grades.
Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities	The following table presents the estimated impact on Prosper Funding’s estimated fair value of servicing assets, calculated using different market servicing rates and different default rates as of September 30, 2019 (in thousands, except percentages): Servicing Assets Fair Value at September 30, 2019 $ 15,220 Market servicing rate assumptions 0.625 % Resulting fair value from: Market servicing rate increase to 0.65% $ 14,274 Market servicing rate decrease to 0.60% $ 16,167 Weighted average prepayment assumptions 21.49 % Resulting fair value from: Applying a 1.1 multiplier to prepayment rate $ 14,557 Applying a 0.9 multiplier to prepayment rate $ 14,952 Weighted average default assumptions 12.70 % Resulting fair value from: Applying a 1.1 multiplier to default rate $ 15,033 Applying a 0.9 multiplier to default rate $ 15,412

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Other Intangible Assets for the Period Presented	The following table presents the detail of other intangible assets for the period presented (dollars in thousands): September 30, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value Remaining Useful Life (In Years) Developed technology $ 3,060 $ (3,060) $ — — User base and customer relationships 5,050 (4,261) 789 5.6 Brand name 60 (60) — — Total Intangible Assets Subject to Amortization $ 8,170 $ (7,381) $ 789
Summary of Estimated Amortization of Purchased Intangible Assets	Estimated amortization of purchased intangible assets for future periods is as follows (in thousands): Year Ending December 31, Estimated Amortization of Purchased Intangible Assets 2019 (remainder thereof) $ 70 2020 219 2021 172 2022 136 2023 107 Thereafter 85 Total $ 789

Other Liabilities (Tables)

Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Other Liabilities [Abstract]
Schedule of Other Liabilities	Other Liabilities includes the following: September 30, 2019 December 31, 2018 Loan trailing fee $ 3,281 $ 3,118 Deferred revenue 297 396 Servicing liabilities 2 12 Deferred income tax liability 392 373 Deferred rent — 3,408 Restructuring liability — 2,106 Operating lease liability 18,570 — Other 1,023 1,216 Total Other Liabilities $ 23,565 $ 10,629

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	Basic and diluted net income (loss) per share was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net income (loss) $ 10,769 $ (19,779) $ (12,514) $ (43,779) Less: net income allocated to participating securities (7,994) — — — Net income (loss) available to common stockholders $ 2,775 $ (19,779) $ (12,514) $ (43,779) Denominator: Weighted average shares used in computing net income (loss) per share - basic 70,606,805 70,394,269 70,532,641 70,353,819 Effect of dilutive securities: Stock options 1,939,105 — — — Convertible preferred stock warrants 213,264,845 — — — Weighted average shares used in computing diluted net income (loss) per share - diluted 285,810,755 70,394,269 70,532,641 70,353,819 Net income (loss) per share - basic $ 0.04 $ (0.28) $ (0.18) $ (0.62) Net income (loss) per share - diluted $ 0.01 $ (0.28) $ (0.18) $ (0.62)
Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share	The following common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (shares) (shares) (shares) (shares) Excluded securities: Convertible preferred stock issued and outstanding 214,637,925 214,637,925 214,637,925 214,637,925 Stock options issued and outstanding 73,211,425 67,566,031 73,029,965 69,486,992 Warrants issued and outstanding 1,080,349 1,080,349 1,080,349 1,082,055 Series E-1 convertible preferred stock warrants 35,544,141 35,544,141 35,544,141 35,544,141 Series F convertible preferred stock warrants 177,720,704 177,720,704 177,720,704 177,720,704 Total common stock equivalents excluded from diluted net loss per common share computation 502,194,544 496,549,150 502,013,084 498,471,817

Convertible Preferred Stock, _2

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit (Tables)	9 Months Ended
	Sep. 30, 2019
Class of Stock [Line Items]
Summary of Shares Authorized, Issued, Outstanding, Par Value and Liquidation Preference of Convertible Preferred Stock	The number of authorized, issued and outstanding shares, their par value and liquidation preference for each series of convertible preferred stock as of September 30, 2019 are disclosed in the table below (amounts in thousands except share and per share amounts): Convertible Preferred Stock Par Value Authorized Shares Outstanding and Issued Shares Liquidation Preference (Outstanding Shares) Series A $ 0.01 68,558,220 68,558,220 $ 19,774 Series A-1 $ 0.01 24,760,915 24,760,915 49,522 Series B $ 0.01 35,775,880 35,775,880 21,581 Series C $ 0.01 24,404,770 24,404,770 70,075 Series D $ 0.01 23,888,640 23,888,640 165,000 Series E-1 $ 0.01 35,544,141 — — Series E-2 $ 0.01 16,858,078 — — Series F $ 0.01 177,720,707 3 — Series G $ 0.01 37,249,497 37,249,497 50,000 444,760,848 214,637,925 $ 375,952
Schedule of Stockholders' Equity Note, Warrants or Rights	The combined activity of the Convertible Preferred Stock Warrant Liability for the nine months ended September 30, 2019 and 2018 are as follows (in thousands): Warrant Activity Balance at January 1, 2019 $ 143,679 Warrants Vested 17,553 Change in Fair Value (8,890) Balance at September 30, 2019 $ 152,342 Warrant Activity Balance at January 1, 2018 $ 116,366 Warrants Vested 55,473 Change in Fair Value (17,885) Balance at September 30, 2018 $ 153,954
Series E-1 Preferred Stock
Class of Stock [Line Items]
Schedule of Assumptions Used	We determined the fair value of the outstanding Series E-1 Warrants utilizing the following assumptions as of the following dates: September 30, 2019 December 31, 2018 Volatility 40% 40% Risk-free interest rate 1.63% 2.62% Remaining contractual term 7.29 years 8.04 years Dividend yield —% —%
Series F convertible preferred stock warrants (in shares)
Class of Stock [Line Items]
Schedule of Assumptions Used	We determined the fair value of the outstanding Series F Warrants utilizing the following assumptions as of the following dates: September 30, 2019 December 31, 2018 Volatility 40% 40% Risk-free interest rate 1.63% 2.63% Remaining contractual term 7.41 years 8.16 years Dividend yield —% —%

Share Based Incentive Plan an_2

Share Based Incentive Plan and Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Summarized Option Activity under Option Plan	Stock option activity under the 2005 Plan and 2015 Plan is summarized for the nine months ended September 30, 2019 below: Options Issued and Outstanding Weighted- Average Exercise Price Balance as of January 1, 2019 71,021,698 $ 0.33 Options issued 8,999,048 $ 0.28 Options exercised (162,356) $ 0.15 Options forfeited (4,531,344) $ 0.40 Options expired (53,700) $ 0.30 Balance as of September 30, 2019 75,273,346 $ 0.32 Options vested and expected to vest as of September 30, 2019 62,244,684 $ 0.32 Options vested and exercisable at September 30, 2019 49,227,760 $ 0.28
Fair Value of Stock Option Awards	The fair value of PMI’s stock option awards granted during the three and nine months ended September 30, 2019 and September 30, 2018 was estimated at the date of grant using the Black-Scholes model with the following average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Volatility of common stock 46.72 % 43.76 % 46.72 % 44.06 % Risk-free interest rate 1.57 % 2.85 % 2.24 % 2.76 % Expected life 6.0 years 6.0 years 5.9 years 6.0 years Dividend yield — % — % — % — %
Summarized Activities for RSU's	The following table summarizes the number of PMI’s outstanding RSUs and their weighted-average grant date fair value during the nine months ended September 30, 2019: Number of Shares Weighted-Average Grant Date Fair Value Unvested - January 1, 2019 4,856,141 $ 0.96 Forfeited (53,000) $ 1.90 Unvested - September 30, 2019 4,803,141 $ 0.95
Stock Based Compensation Included in Consolidated Statements of Operations	The following table presents the amount of stock-based compensation related to stock-based awards granted to employees recognized in Prosper’s condensed consolidated statements of operations during the three and nine months ended September 30, 2019 and September 30, 2018 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Origination and servicing $ 73 $ 213 $ 377 $ 670 Sales and marketing 71 108 216 324 General and administrative 844 1,507 3,245 5,418 Total stock based compensation $ 988 $ 1,828 $ 3,838 $ 6,412

Consortium Purchase Agreement (

Consortium Purchase Agreement (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Consortium Purchase Agreement	The following represents the loans purchased and warrants vested under the Consortium Purchase Agreement through its expiration in May 2019: Loans Acquired Warrants Vested Balance as of January 1, 2019 $ 3,067,332 $ 154,912,980 Nine Months Ended September 30, 2019 235,951 22,807,726 Balance as of September 30, 2019 $ 3,303,283 $ 177,720,706

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Operating Lease Right-of-Use Assets	The following represents the operating lease right-of-use assets as of September 30, 2019, which are included in "Property and Equipment, Net" on the condensed consolidated balance sheets. September 30, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value ROU Assets - Office buildings $ 15,846 $ 2,296 $ 13,550 ROU Assets - Other 292 173 119 Total right-of-use assets subject to amortization $ 16,138 $ 2,469 $ 13,669
Future Minimum Lease Payments Under Topic 842	Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows (in thousands). The present value of the future minimum lease payments represent our lease liabilities as of September 30, 2019 and are included in "Other Liabilities" on the condensed consolidated balance sheets. Minimum Lease Payments Remainder of 2019 $ 1,328 2020 5,240 2021 5,134 2022 5,018 2023 1,567 Thereafter 2,546 Total future minimum lease payments $ 20,833 Less imputed interest (2,263) Present value of future minimum lease payments $ 18,570
Future Minimum Lease Payments Under Topic 840	The table below presents future minimum rental payments at December 31, 2018, net of minimum sublease rentals of $5.3 million, for the remaining terms of the operating leases (in thousands): 2019 $ 4,536 2020 4,683 2021 4,456 2022 4,319 2023 847 Thereafter 387 Total future operating lease obligations $ 19,228
Other Information Related to Leases	Other information related to leases was as follows ($ in thousands): September 30, 2019 Cash paid for operating leases year-to-date $ 3,903 Right of use assets obtained in exchange for new operating lease obligations (1) $ 21,630 Weighted average remaining lease term 4.31 years Weighted average discount rate 5.53 %

Related Parties (Tables)

Related Parties (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Aggregate Amount of Notes Purchased and the Income Earned	The aggregate amount of the Notes and Borrower Loans purchased and the income earned by parties deemed to be affiliates and related parties of Prosper for the three and nine months ended September 30, 2019 and September 30, 2018, as well as the Notes and Borrower Loans outstanding as of September 30, 2019 and December 31, 2018 are summarized below (in thousands): Aggregate Amount of Interest Earned on Related Party 2019 2018 2019 2018 Executive officers and management $ 6 $ 3 $ 1 $ — Directors (excluding executive officers and management) 101 107 13 11 Total $ 107 $ 110 $ 14 $ 11 Aggregate Amount of Notes and Borrower Loans Purchased Nine Months Ended September 30, Interest Earned on Notes and Borrower Loans Nine Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 17 $ 12 $ 4 $ 1 Directors (excluding executive officers and management) 309 315 37 33 Total $ 326 $ 327 $ 41 $ 34 Notes Balance as of Related Party September 30, 2019 December 31, 2018 Executive officers and management $ 35 $ 32 Directors (excluding executive officers and management) 618 569 $ 653 $ 601
Prosper Funding LLC
Entity Information [Line Items]
Aggregate Amount of Notes Purchased and the Income Earned	The aggregate amount of the Notes and Borrower Loans purchased and the income earned by parties deemed to be related parties of Prosper Funding as of September 30, 2019 and December 31, 2018 are summarized below (in thousands): Aggregate Amount of Notes and Borrower Loans Purchased Interest Earned on Three Months Ended September 30, Three Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 6 $ 3 $ 1 $ — Directors (excluding executive officers and management) — — — — Total $ 6 $ 3 $ 1 $ — Aggregate Amount of Notes and Borrower Loans Purchased Interest Earned on Nine Months Ended September 30, Nine Months Ended September 30, Related Party 2019 2018 2019 2018 Executive officers and management $ 17 $ 12 $ 4 $ 1 Directors (excluding executive officers and management) — — — — Total $ 17 $ 12 $ 4 $ 1 Note and Borrower Loan Balance as of Related Party September 30, 2019 December 31, 2018 Executive officers and management $ 35 $ 32 Directors (excluding executive officers and management) — — $ 35 $ 32

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2019		Dec. 31, 2018		Sep. 30, 2018	Dec. 31, 2017
Entity Information [Line Items]
Cash and Cash Equivalents	$ 55,300		$ 57,945		$ 58,447	$ 45,795
Restricted Cash (1)	158,302	[1]	149,114	[1]	145,233	152,668
Total Cash, Cash Equivalents and Restricted Cash shown in the consolidated statements of cash flows	213,602		207,059		203,680	198,463
Prosper Funding LLC
Entity Information [Line Items]
Cash and Cash Equivalents	13,716		11,163		9,643	8,223
Restricted Cash (1)	125,442		136,018		132,573	140,092
Total Cash, Cash Equivalents and Restricted Cash shown in the consolidated statements of cash flows	$ 139,158		$ 147,181		$ 142,216	$ 148,315
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2019		Jan. 01, 2019	Dec. 31, 2018		Sep. 30, 2018	Dec. 31, 2017
Entity Information [Line Items]
Restricted Cash (1)	$ 158,302	[1]		$ 149,114	[1]	$ 145,233	$ 152,668
Operating Leases, Future Minimum Payments Due	19,228
Gross Carrying Value	16,138
Operating lease liability	18,570
Reduction in other liabilities	(23,565)			(10,629)
Accounting Standards Update 2016-02
Entity Information [Line Items]
Gross Carrying Value			$ 16,100
Operating lease liability			21,600
Reduction in other liabilities			$ 5,100
Prosper Funding LLC
Entity Information [Line Items]
Restricted Cash (1)	125,442			136,018		$ 132,573	$ 140,092
Reduction in other liabilities	$ (4,564)			$ (4,528)
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 68,522		$ 68,522		$ 50,615
Less accumulated depreciation and amortization	(37,223)		(37,223)		(35,342)
Total Property and Equipment, Net	31,299		31,299		15,273
Depreciation expense			5,649	$ 7,708
Property Plant And Equipment
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	1,800	$ 2,300	5,400	7,400
Operating lease right-of-use assets
Property, Plant and Equipment [Line Items]
Property and equipment	16,138		16,138		0
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	12,797		12,797		15,193
Internal-use software and website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	24,783		24,783		22,505
Capitalized internal-use software and website development costs	2,600	1,500	6,900	4,000
Office equipment and furniture
Property, Plant and Equipment [Line Items]
Property and equipment	2,999		2,999		3,015
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	7,158		7,158		7,157
Assets not yet placed in service
Property, Plant and Equipment [Line Items]
Property and equipment	4,647		4,647		2,745
Prosper Funding LLC
Property, Plant and Equipment [Line Items]
Less accumulated depreciation and amortization	(16,626)		(16,626)		(16,079)
Total Property and Equipment, Net	4,932		4,932		6,426
Depreciation expense	1,100	$ 1,300	3,279	$ 4,282
Prosper Funding LLC | Internal-use software and website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	$ 21,558		$ 21,558		$ 22,505

Borrower Loans, Loans Held fo_3

Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value - Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans Receivable at Fair Value	[1]	$ 540,969	$ 263,522
Notes, at Fair Value		(247,725)	(264,003)
Loans Held for Sale, at Fair Value (1)	[1]	231,644	183,788
Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans Receivable at Fair Value		247,718	263,522
Notes, at Fair Value		(247,725)	(264,003)
Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal balance outstanding, Notes		(254,369)	(272,430)
Fair value adjustments, Notes		6,644	8,427
Notes, at Fair Value		(247,725)	(264,003)
Notes | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal balance outstanding, Notes		(254,369)	(272,430)
Fair value adjustments, Notes		6,644	8,427
Notes, at Fair Value		(247,725)	(264,003)
Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal balance outstanding		554,208	269,093
Fair value adjustments		(13,239)	(5,571)
Borrower Loans Receivable at Fair Value		540,969	263,522
Borrower Loans | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal balance outstanding		251,796	269,093
Fair value adjustments		(4,078)	(5,571)
Borrower Loans Receivable at Fair Value		247,718	263,522
Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fair value adjustments		(34)	(1,869)
Aggregate principal balance outstanding, Loans Held for Sale		231,678	185,657
Loans Held for Sale, at Fair Value (1)		$ 231,644	$ 183,788
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Borrower Loans, Loans Held fo_4

Borrower Loans, Loans Held for Sale, and Notes Held at Fair Value - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loss related to credit risks on borrower loans			$ 4,200	$ 600
Interest income	$ 11,774	$ 3,316	$ 24,980	8,033
Minimum number of days for which loans originated were delinquent			90 days		90 days
Aggregate principal amount of loans originated that are 90 days or more delinquent	6,000		$ 6,000		$ 2,500
Fair value of loans originated that are 90 days or more delinquent	2,400		$ 2,400		1,100
Non accrual status past due date			120 days
Borrower loans in non-accrual status	600		$ 600		300
Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fair value adjustments			(34)		$ (1,869)
Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loss related to credit risks on borrower loans			2,500	600
Interest income	657	$ 730	$ 2,007	2,200
Minimum number of days for which loans originated were delinquent			90 days		90 days
Aggregate principal amount of loans originated that are 90 days or more delinquent	2,400		$ 2,400		$ 2,500
Fair value of loans originated that are 90 days or more delinquent	1,000		$ 1,000		1,100
Non accrual status past due date			120 days
Borrower loans in non-accrual status	300		$ 300		$ 300
Outstanding Borrower Loans and Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum			5.31%		5.31%
Fixed interest rate, maximum			31.92%		31.92%
Loans Held For Sale Borrower Loans And Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum			5.31%		5.31%
Fixed interest rate, maximum			31.82%		31.82%
Interest income			$ 13,100	$ 9,200
Aggregate principal amount of loans originated that are 90 days or more delinquent	500		500		$ 800
Fair value of loans originated that are 90 days or more delinquent	$ 200		$ 200		$ 300
Loans Held For Sale Borrower Loans And Underlying Notes | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum			5.31%		5.31%
Fixed interest rate, maximum			31.92%		31.92%
Minimum | Outstanding Borrower Loans and Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			36 months		36 months
Minimum | Loans Held For Sale Borrower Loans And Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			36 months		36 months
Minimum | Loans Held For Sale Borrower Loans And Underlying Notes | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			36 months		36 months
Maximum | Outstanding Borrower Loans and Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			60 months		60 months
Maximum | Loans Held For Sale Borrower Loans And Underlying Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			60 months		60 months
Maximum | Loans Held For Sale Borrower Loans And Underlying Notes | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months			60 months		60 months

Loan Servicing Assets and Lia_2

Loan Servicing Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Servicing Assets And Liabilities Fair Value [Line Items]
Gain (loss) on sale of borrower loans	$ 2,577	$ 3,139	$ 8,834	$ 10,652
Fair value of warrants vested on sale of borrower loans	0	19,561	17,553	55,473
Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Gain (loss) on sale of borrower loans	3,155	(16,379)	(7,725)	(44,133)
Borrower Loans
Servicing Assets And Liabilities Fair Value [Line Items]
Outstanding principle	3,200,000		$ 3,200,000		$ 3,600,000
Fixed interest rate, minimum			5.31%		5.31%
Fixed interest rate, maximum			31.92%		35.52%
Contractually specified servicing fees, late charges and ancillary fees			$ 27,800	32,500
Borrower Loans | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Outstanding principle	3,800,000		$ 3,800,000		$ 3,700,000
Fixed interest rate, minimum			5.31%		5.31%
Fixed interest rate, maximum			31.92%		35.52%
Contractually specified servicing fees, late charges and ancillary fees	$ 10,700	$ 11,300	$ 31,000	$ 33,100
Minimum | Borrower Loans
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months			36 months		36 months
Minimum | Borrower Loans | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months			36 months		36 months
Maximum | Borrower Loans
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months			60 months		60 months
Maximum | Borrower Loans | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months			60 months		60 months

Available for Sale Investment_3

Available for Sale Investments, at Fair Value - Schedule of Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Available for Sale Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 1,500	$ 22,173
Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,500	22,186
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(13)
Fair Value	1,500	22,173
Treasury Bills | Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	0	17,940
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(3)
Fair Value	0	17,937
US Treasury securities | Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,500	4,246
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(10)
Fair Value	$ 1,500	$ 4,236

Available for Sale Investment_4

Available for Sale Investments, at Fair Value - Summary of Available for Sale Investments of Continuous Unrealized Loss (Details) - Fixed Maturity Securities $ in Thousands	Dec. 31, 2018USD ($)
Schedule Of Available For Sale Securities [Line Items]
Fair value, less than 12 months	$ 17,937
Unrealized losses, less than 12 months	(3)
Fair value, 12 months or longer	4,236
Unrealized losses, 12 months or longer	(10)
Total, fair value	22,173
Total, unrealized losses	(13)
Treasury Bills
Schedule Of Available For Sale Securities [Line Items]
Fair value, less than 12 months	17,937
Unrealized losses, less than 12 months	(3)
Fair value, 12 months or longer	0
Unrealized losses, 12 months or longer	0
Total, fair value	17,937
Total, unrealized losses	(3)
US Treasury securities
Schedule Of Available For Sale Securities [Line Items]
Fair value, less than 12 months	0
Unrealized losses, less than 12 months	0
Fair value, 12 months or longer	4,236
Unrealized losses, 12 months or longer	(10)
Total, fair value	4,236
Total, unrealized losses	$ (10)

Available for Sale Investment_5

Available for Sale Investments, at Fair Value - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Impairment charges recognized during period	$ 0	$ 0
Proceeds from investments	$ 0	$ 0

Available for Sale Investment_6

Available for Sale Investments, at Fair Value - Schedule of Maturities of Available for Sale Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Total	$ 1,500	$ 22,173
Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Within 1 year	1,500	22,173
After 1 year through 5 years	0	0
After 5 years to 10 years	0	0
After 10 years	0	0
Total	1,500	22,173
Amortized cost within 1 year	1,500	22,186
Amortized cost after 1 year through 5 years	0	0
Amortized cost after 5 years to 10 years	0	0
Amortized cost after 10 years	0	0
Amortized Cost	1,500	22,186
Treasury Bills | Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Within 1 year	0	17,937
After 1 year through 5 years	0	0
After 5 years to 10 years	0	0
After 10 years	0	0
Total	0	17,937
Amortized Cost	0	17,940
US Treasury securities | Fixed Maturity Securities
Schedule Of Available For Sale Securities [Line Items]
Within 1 year	1,500	4,236
After 1 year through 5 years	0	0
After 5 years to 10 years	0	0
After 10 years	0	0
Total	1,500	4,236
Amortized Cost	$ 1,500	$ 4,246

Securitization - Additional Inf

Securitization - Additional Information (Details) - USD ($) $ in Thousands		May 23, 2019	Feb. 07, 2019	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Notes issued	[1]			$ 260,060	$ 0
Borrower Loans	[1]			540,969	263,522
Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued	[2]			260,060	0
Borrower Loans	[2]			293,252	$ 0
Securtization Trust PMT2019-1 | Primary Beneficiary
Variable Interest Entity [Line Items]
Securitization amount			$ 205,100
Net proceeds on sale of notes to third party			$ 171,700
Ownership percentage			65.50%
Debt issuance costs			$ 2,300
Unamortized debt issuance costs				115,600
Borrower Loans				128,500
2019-1, Class A Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued			$ 127,300
Interest rate			3.54%
2019-1, Class B Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued			$ 25,000
Interest rate			4.03%
2019-1, Class C Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued			$ 19,300
Interest rate			5.27%
Securitization Trust 2019-2 | Primary Beneficiary
Variable Interest Entity [Line Items]
Securitization amount		$ 203,500
Net proceeds on sale of notes to third party		$ 174,200
Ownership percentage		16.40%
Debt issuance costs		$ 1,900
Unamortized debt issuance costs				144,500
Borrower Loans				$ 164,800
2019-2, Class A Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued		$ 110,100
Interest rate		3.20%
2019-2, Class B Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued		$ 31,400
Interest rate		3.69%
2019-2, Class C Notes | Primary Beneficiary
Variable Interest Entity [Line Items]
Notes issued		$ 32,700
Interest rate		5.05%
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.
[2]	The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 7 - Securitizations and Note 11 - Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information.

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Assets:
Borrower Loans	[1]	$ 540,969	$ 263,522
Loans Held for Sale, at Fair Value (1)	[1]	231,644	183,788
Available for Sale Investments, at Fair Value		1,500	22,173
Servicing Assets		12,936	14,687
Total Assets		787,049	484,170
Liabilities:
Notes		247,725	264,003
Servicing Liabilities		2	12
Certificates Issued by Securitization Trust, at Fair Value	[1]	37,564	0
Convertible Preferred Stock Warrant Liability		152,342	143,679
Loan Trailing Fee Liability		3,281	3,118
Total Liabilities		440,914	410,812
Prosper Funding LLC
Assets:
Borrower Loans		247,718	263,522
Servicing Assets		15,220	15,550
Total Assets		262,938	279,072
Liabilities:
Notes		247,725	264,003
Servicing Liabilities		2	12
Loan Trailing Fee Liability		3,281	3,118
Total Liabilities		251,008	267,133
Level 1 Inputs
Assets:
Borrower Loans		0	0
Loans Held for Sale, at Fair Value (1)		0	0
Available for Sale Investments, at Fair Value		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes		0	0
Servicing Liabilities		0	0
Certificates Issued by Securitization Trust, at Fair Value		0
Convertible Preferred Stock Warrant Liability		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 1 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes		0	0
Servicing Liabilities		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 2 Inputs
Assets:
Borrower Loans		0	0
Loans Held for Sale, at Fair Value (1)		0	0
Available for Sale Investments, at Fair Value		1,500	22,173
Servicing Assets		0	0
Total Assets		1,500	22,173
Liabilities:
Notes		0	0
Servicing Liabilities		0	0
Certificates Issued by Securitization Trust, at Fair Value		0
Convertible Preferred Stock Warrant Liability		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 2 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes		0	0
Servicing Liabilities		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 3 Inputs
Assets:
Borrower Loans		540,969	263,522
Loans Held for Sale, at Fair Value (1)		231,644	183,788
Available for Sale Investments, at Fair Value		0	0
Servicing Assets		12,936	14,687
Total Assets		785,549	461,997
Liabilities:
Notes		247,725	264,003
Servicing Liabilities		2	12
Certificates Issued by Securitization Trust, at Fair Value		37,564
Convertible Preferred Stock Warrant Liability		152,342	143,679
Loan Trailing Fee Liability		3,281	3,118
Total Liabilities		440,914	410,812
Level 3 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		247,718	263,522
Servicing Assets		15,220	15,550
Total Assets		262,938	279,072
Liabilities:
Notes		247,725	264,003
Servicing Liabilities		2	12
Loan Trailing Fee Liability		3,281	3,118
Total Liabilities		$ 251,008	$ 267,133
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Borrower Loans, Loans Held For Sale and Notes - Quantitative Information about the Significant Unobservable Inputs (Details)	Sep. 30, 2019	Dec. 31, 2018
Discount rate | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.047	0.047
Discount rate | Minimum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Minimum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.047	0.047
Discount rate | Minimum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.123	0.138
Discount rate | Maximum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.250	0.250
Discount rate | Maximum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.122	0.138
Discount rate | Maximum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.250	0.250
Default rate | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.021	0.020
Default rate | Minimum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.018	0.016
Default rate | Minimum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.023	0.020
Default rate | Minimum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.018	0.016
Default rate | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.184	0.158
Default rate | Maximum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.188	0.167
Default rate | Maximum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.177	0.158
Default rate | Maximum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.188	0.167
Prepayment rate | Minimum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.165	0.155
Prepayment rate | Minimum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.165	0.155
Prepayment rate | Maximum | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.278	0.251
Prepayment rate | Maximum | Prosper Funding LLC | Obligations
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.278	0.251

Fair Value of Assets and Liab_5

Fair Value of Assets and Liabilities - Servicing Rights - Quantitative Information about the Significant Unobservable Inputs (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Servicing Rights at Fair Value [Line Items]
Market servicing rate	0.625%	0.625%
Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Market servicing rate	0.625%	0.625%
Minimum
Servicing Rights at Fair Value [Line Items]
Discount rate	15.00%	15.00%
Default rate	1.80%	1.60%
Prepayment rate	16.50%	15.50%
Minimum | Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Discount rate	15.00%	15.00%
Default rate	1.80%	1.60%
Prepayment rate	16.50%	15.50%
Maximum
Servicing Rights at Fair Value [Line Items]
Discount rate	25.00%	25.00%
Default rate	18.80%	16.70%
Prepayment rate	27.80%	25.10%
Maximum | Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Discount rate	25.00%	25.00%
Default rate	18.80%	16.70%
Prepayment rate	27.80%	25.10%

Fair Value of Assets and Liab_6

Fair Value of Assets and Liabilities - Loan Trailing Fee Liability (Details)	Sep. 30, 2019	Dec. 31, 2018
Discount rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.047	0.047
Discount rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.123	0.138
Discount rate | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.047	0.047
Discount rate | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.122	0.138
Discount rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.250	0.250
Discount rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.250	0.250
Default rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.021	0.020
Default rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.184	0.158
Default rate | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.023	0.020
Default rate | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.177	0.158
Default rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.018	0.016
Default rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.188	0.167
Default rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.018	0.016
Default rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.188	0.167
Prepayment rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.165	0.155
Prepayment rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.278	0.251
Prepayment rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.165	0.155
Prepayment rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.278	0.251

Fair Value of Assets and Liab_7

Fair Value of Assets and Liabilities - Summary of Level 3 Borrower Loans, Loans Held for Sale and Notes, Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Asset And Liability [Roll Forward]
Beginning balance, Total	$ 424,246	$ 116,753	$ 183,307	$ (894)
Purchase of Borrower Loans/Issuance of Notes	647,917	542,709	2,019,475	1,867,191
Transfers in (Transfers out)			0
Principal repayments	(61,762)	(11,826)	(132,322)	(23,513)
Borrower Loans sold to third parties	(513,122)	(531,339)	(1,568,316)	(1,727,006)
Other changes	1,259	88	1,439	1,179
Change in fair value	(11,214)	(3,229)	(16,259)	(3,801)
Ending balance, Total	487,324	113,156	487,324	113,156
Prosper Funding LLC
Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Asset And Liability [Roll Forward]
Beginning balance, Total	645	(33)	(481)	(894)
Originations	(647,917)	(542,709)	1,808,503	1,867,191
Principal repayments	393	1,273	3,707	3,837
Borrower Loans sold to third parties	(648,751)	(543,742)	(1,811,711)	(1,869,858)
Other changes	(91)	15	312	310
Change in fair value	(120)	(250)	(337)	(614)
Ending balance, Total	(7)	(28)	(7)	(28)
Notes
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, Liabilities	(253,425)	(277,425)	(264,003)	(293,948)
Purchase of Borrower Loans/Issuance of Notes	(41,439)	(43,797)	(128,152)	(134,490)
Transfers in (Transfers out)			0
Principal repayments	40,993	43,418	126,721	134,943
Borrower Loans sold to third parties	0	0	0	0
Other changes	(65)	(9)	538	624
Change in fair value	6,211	9,225	17,171	24,283
Ending balance, Liabilities	(247,725)	(268,588)	(247,725)	(268,588)
Notes | Prosper Funding LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, Liabilities	(253,425)	(277,425)	(264,003)	(293,948)
Originations	(41,439)	(43,797)	(128,152)	(134,490)
Principal repayments	40,993	43,418	126,721	134,943
Borrower Loans sold to third parties	0	0	0	0
Other changes	(65)	(9)	538	624
Change in fair value	6,211	9,225	17,171	24,283
Ending balance, Liabilities	(247,725)	(268,588)	(247,725)	(268,588)
Certificates Issued by Securitization Trust
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, Liabilities	(44,090)		0
Purchase of Borrower Loans/Issuance of Notes	0		(51,595)
Transfers in (Transfers out)			0
Principal repayments	4,173		8,445
Borrower Loans sold to third parties	0		0
Other changes	252		(351)
Change in fair value	2,101		5,937
Ending balance, Liabilities	(37,564)		(37,564)
Borrower Loans
Changes in Level 3 assets measured at fair value on a recurring basis [Abstract]
Beginning balance, Assets	606,799	277,361	263,522	293,005
Purchases	41,460	43,596	390,089	134,671
Transfers in (Transfers out)			147,773
Principal repayments	(87,348)	(42,139)	(221,379)	(131,086)
Borrower loans sold to third parties	(1,526)	(843)	(3,412)	(2,859)
Other changes	240	24	331	(314)
Change in fair value	(18,656)	(9,450)	(35,955)	(24,868)
Ending balance, Assets	540,969	268,549	540,969	268,549
Borrower Loans | Prosper Funding LLC
Changes in Level 3 assets measured at fair value on a recurring basis [Abstract]
Beginning balance, Assets	254,070	277,361	263,522	293,005
Originations	41,460	43,596	127,522	134,671
Principal repayments	(40,600)	(42,139)	(123,014)	(131,086)
Borrower loans sold to third parties	(855)	(843)	(2,578)	(2,859)
Other changes	(26)	24	(226)	(314)
Change in fair value	(6,331)	(9,450)	(17,508)	(24,868)
Ending balance, Assets	247,718	268,549	247,718	268,549
Loans Held for Sale
Changes in Level 3 assets measured at fair value on a recurring basis [Abstract]
Beginning balance, Assets	114,962	116,817	183,788	49
Purchases	647,896	542,910	1,809,133	1,867,010
Transfers in (Transfers out)			(147,773)
Principal repayments	(19,580)	(13,105)	(46,109)	(27,370)
Borrower loans sold to third parties	(511,596)	(530,496)	(1,564,904)	(1,724,147)
Other changes	832	73	921	869
Change in fair value	(870)	(3,004)	(3,412)	(3,216)
Ending balance, Assets	231,644	113,195	231,644	113,195
Loans Held for Sale | Prosper Funding LLC
Changes in Level 3 assets measured at fair value on a recurring basis [Abstract]
Beginning balance, Assets	0	31	0	49
Originations	647,896	542,910	1,809,133	1,867,010
Principal repayments	0	(6)	0	(20)
Borrower loans sold to third parties	(647,896)	(542,899)	(1,809,133)	(1,866,999)
Other changes	0	0	0	0
Change in fair value	0	(25)	0	(29)
Ending balance, Assets	$ 0	$ 11	$ 0	$ 11

Fair Value of Assets and Liab_8

Fair Value of Assets and Liabilities - Schedule of Servicing Assets and Liabilities, Warrant Liability and Loan Trailing (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance			$ 14,687
Servicing Asset at Fair Value, Ending Balance	$ 12,936		12,936
Prosper Funding LLC
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance			15,550
Servicing Asset at Fair Value, Ending Balance	15,220		15,220
Servicing Assets
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance	13,387	$ 15,644	14,687	$ 14,711
Additions	2,859	3,156	9,237	10,658
Derecognition			(1,049)	0
Less: Changes in fair value	(3,310)	(3,362)	(9,939)	(9,931)
Servicing Asset at Fair Value, Ending Balance	12,936	15,438	12,936	15,438
Servicing Assets | Prosper Funding LLC
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance	15,461	16,162	15,550	14,598
Additions	3,436	3,198	10,232	11,345
Less: Changes in fair value	(3,677)	(3,430)	(10,562)	(10,013)
Servicing Asset at Fair Value, Ending Balance	15,220	15,930	15,220	15,930
Mandatorily Redeemable Preferred Stock
Liabilities at Fair Value, Amount [Roll Forward]
Beginning balance	166,559	143,676	143,679	116,366
Issuances	0	19,561	17,553	55,473
Change in fair value	(14,217)	(9,283)	(8,890)	(17,885)
Ending balance	152,342	$ 153,954	152,342	$ 153,954
Loan Trailing Fee Liability
Liabilities at Fair Value, Amount [Roll Forward]
Beginning balance			3,118
Issuances			2,063
Cash payment of Loan Trailing Fee			(1,744)
Change in fair value			(156)
Ending balance	3,281		3,281
Loan Trailing Fee Liability | Prosper Funding LLC
Liabilities at Fair Value, Amount [Roll Forward]
Beginning balance			3,118
Issuances			2,063
Cash payment of Loan Trailing Fee			1,744
Change in fair value			(156)
Ending balance	3,281		3,281
Level 3 Inputs
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance			14,687
Servicing Asset at Fair Value, Ending Balance	12,936		12,936
Level 3 Inputs | Prosper Funding LLC
Servicing Asset at Fair Value, Amount [Roll Forward]
Servicing Asset at Fair Value, Beginning Balance			15,550
Servicing Asset at Fair Value, Ending Balance	$ 15,220		$ 15,220

Fair Value of Assets and Liab_9

Fair Value of Assets and Liabilities - Fair Value Assumptions for Borrower Loans, Loans Held for Sale and Notes (Details) $ in Thousands	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	$ 247,725	$ 264,003
Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	247,725	$ 264,003
Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	247,725
Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	247,725
Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	772,613
Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value	247,718
Discount rate assumption | 100 basis point increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	245,448
Discount rate assumption | 100 basis point increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	245,448
Discount rate assumption | 100 basis point increase | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	765,521
Discount rate assumption | 100 basis point increase | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	245,444
Discount rate assumption | 200 basis point increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	243,225
Discount rate assumption | 200 basis point increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	243,225
Discount rate assumption | 200 basis point increase | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	758,597
Discount rate assumption | 200 basis point increase | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	243,224
Discount rate assumption | 100 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	250,059
Discount rate assumption | 100 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	250,059
Discount rate assumption | 100 basis point decrease | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	779,880
Discount rate assumption | 100 basis point decrease | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	250,048
Discount rate assumption | 200 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	252,450
Discount rate assumption | 200 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	252,450
Discount rate assumption | 200 basis point decrease | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	787,326
Discount rate assumption | 200 basis point decrease | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	252,435
Default rate assumption | 100 basis point increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	244,453
Default rate assumption | 100 basis point increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	244,453
Default rate assumption | 100 basis point increase | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	762,459
Default rate assumption | 100 basis point increase | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	244,463
Default rate assumption | 200 basis point increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	241,278
Default rate assumption | 200 basis point increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	241,278
Default rate assumption | 200 basis point increase | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	752,608
Default rate assumption | 200 basis point increase | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	241,304
Default rate assumption | 100 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	251,059
Default rate assumption | 100 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	251,059
Default rate assumption | 100 basis point decrease | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	782,961
Default rate assumption | 100 basis point decrease | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	251,036
Default rate assumption | 200 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	254,417
Default rate assumption | 200 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes	254,417
Default rate assumption | 200 basis point decrease | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	793,379
Default rate assumption | 200 basis point decrease | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans	$ 254,376
Discount rate | Discount rate assumption | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.0690
Discount rate | Discount rate assumption | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.0690
Discount rate | Discount rate assumption | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.0703
Discount rate | Discount rate assumption | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.0690
Default rate | Default rate assumption | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.1350
Default rate | Default rate assumption | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.1350
Default rate | Default rate assumption | Borrower Loans and Loans Held for Sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.1227
Default rate | Default rate assumption | Borrower Loans and Loans Held for Sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions	0.1350

Fair Value of Assets and Lia_10

Fair Value of Assets and Liabilities - Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	$ 12,936	$ 14,687
Servicing Liabilities	$ 2	$ 12
Market servicing rate assumptions	0.625%	0.625%
Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	$ 15,220	$ 15,550
Servicing Liabilities	$ 2	$ 12
Market servicing rate assumptions	0.625%	0.625%
Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	$ 12,936	$ 14,687	$ 13,387	$ 15,438	$ 15,644	$ 14,711
Market servicing rate assumptions	0.625%
Resulting fair value from:
Market servicing rate increase to 0.65%	$ 12,148
Market servicing rate decrease to 0.60%	$ 13,758
Weighted average prepayment assumptions	21.49%
Resulting fair value from:
Weighted average default assumptions	12.70%
Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	$ 15,220	$ 15,550	$ 15,461	$ 15,930	$ 16,162	$ 14,598
Market servicing rate assumptions	0.625%
Resulting fair value from:
Market servicing rate increase to 0.65%	$ 14,274
Market servicing rate decrease to 0.60%	$ 16,167
Weighted average prepayment assumptions	21.49%
Resulting fair value from:
Weighted average default assumptions	12.70%
Prepayment rate assumption | Servicing Assets | Applying a 1.1 multiplier to prepayment rate
Resulting fair value from:
Servicing Asset, Applying a 1.1 multiplier to prepayment rate	$ 12,781
Prepayment rate assumption | Servicing Assets | Applying a 1.1 multiplier to prepayment rate | Prosper Funding LLC
Resulting fair value from:
Servicing Asset, Applying a 1.1 multiplier to prepayment rate	14,557
Prepayment rate assumption | Servicing Assets | Applying a 0.9 multiplier to prepayment rate
Resulting fair value from:
Servicing Asset, Applying a 0.9 multiplier to prepayment rate	13,127
Prepayment rate assumption | Servicing Assets | Applying a 0.9 multiplier to prepayment rate | Prosper Funding LLC
Resulting fair value from:
Servicing Asset, Applying a 0.9 multiplier to prepayment rate	14,952
Default rate assumption | Servicing Assets | Applying a 1.1 multiplier to default rate
Applying Multiplier, Default Rate [Abstract]
Servicing Asset, Applying a 1.1 multiplier to default rate	12,793
Default rate assumption | Servicing Assets | Applying a 1.1 multiplier to default rate | Prosper Funding LLC
Applying Multiplier, Default Rate [Abstract]
Servicing Asset, Applying a 1.1 multiplier to default rate	15,033
Default rate assumption | Servicing Assets | Applying a 0.9 multiplier to default rate
Applying Multiplier, Default Rate [Abstract]
Servicing Asset, Applying a 0.9 multiplier to default rate	13,116
Default rate assumption | Servicing Assets | Applying a 0.9 multiplier to default rate | Prosper Funding LLC
Applying Multiplier, Default Rate [Abstract]
Servicing Asset, Applying a 0.9 multiplier to default rate	$ 15,412

Fair Value of Assets and Lia_11

Fair Value of Assets and Liabilities - Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities Additional Info (Details)	9 Months Ended
	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rate increase	0.65%
Servicing rate decrease	0.60%
Prepayment rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate increase	1.10%
Prepayment rate decrease	0.90%
Default rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Default rate increase	1.10%
Default rate decrease	0.90%
Prosper Funding LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rate increase	0.65%
Servicing rate decrease	0.60%
Prosper Funding LLC | Prepayment rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate increase	1.10%
Prepayment rate decrease	0.90%
Prosper Funding LLC | Default rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Default rate increase	1.10%
Default rate decrease	0.90%

Fair Value of Assets and Lia_12

Fair Value of Assets and Liabilities - Financial Instruments, Assets and Liabilities not Recorded at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2019		Dec. 31, 2018		Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and Cash Equivalents		$ 55,300		$ 57,945		$ 58,447	$ 45,795
Restricted Cash (1)		158,302	[1]	149,114	[1]	$ 145,233	$ 152,668
Accounts Receivable (1)	[1]	1,670		5,119
Total Assets		1,077,825		753,631
Liabilities:
Accounts Payable and Accrued Liabilities		20,305		19,967
Payable to Investors		113,507		127,538
Notes Issued by Securitization Trust (1)	[1]	260,060		0
Warehouse Lines (1)	[1]	205,818		162,488
Total Liabilities		1,060,886		728,304
Carrying Amount
Assets
Total Assets		215,272		212,178
Liabilities:
Total Liabilities		599,690		309,993
Balance at Fair Value
Assets
Cash and Cash Equivalents		55,300		57,945
Restricted Cash (1)		158,302		149,114
Accounts Receivable (1)		1,670		5,119
Total Assets		215,272		212,178
Liabilities:
Accounts Payable and Accrued Liabilities		20,305		19,967
Payable to Investors		113,507		127,538
Notes Issued by Securitization Trust (1)		265,207
Warehouse Lines (1)		205,818		162,488
Total Liabilities		604,837		309,993
Level 1 Inputs
Assets
Cash and Cash Equivalents		55,300		57,945
Restricted Cash (1)		0		0
Accounts Receivable (1)		0		0
Total Assets		55,300		57,945
Liabilities:
Accounts Payable and Accrued Liabilities		0		0
Payable to Investors		0		0
Notes Issued by Securitization Trust (1)		0
Warehouse Lines (1)		0		0
Total Liabilities		0		0
Level 2 Inputs
Assets
Cash and Cash Equivalents		0		0
Restricted Cash (1)		158,302		149,114
Accounts Receivable (1)		1,670		5,119
Total Assets		159,972		154,233
Liabilities:
Accounts Payable and Accrued Liabilities		20,305		19,967
Payable to Investors		113,507		127,538
Notes Issued by Securitization Trust (1)		265,207
Warehouse Lines (1)		205,818		162,488
Total Liabilities		604,837		309,993
Level 3 Inputs
Assets
Cash and Cash Equivalents		0		0
Restricted Cash (1)		0		0
Accounts Receivable (1)		0		0
Total Assets		0		0
Liabilities:
Accounts Payable and Accrued Liabilities		0		0
Payable to Investors		0		0
Notes Issued by Securitization Trust (1)		0
Warehouse Lines (1)		0		0
Total Liabilities		$ 0		$ 0
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 36,368		$ 36,368		$ 36,368
Intangible assets, net	789		789		$ 999
Amortization of intangible assets	100	$ 100	200	$ 300
User base and customer relationships
Goodwill And Other Intangible Assets [Line Items]
Intangible assets, net	$ 789		$ 789
Intangible assets amortized period			5 years 7 months 6 days
User base and customer relationships | Minimum
Goodwill And Other Intangible Assets [Line Items]
Intangible assets amortized period	3 years
User base and customer relationships | Maximum
Goodwill And Other Intangible Assets [Line Items]
Intangible assets amortized period	10 years

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Summary of Other Intangible Assets for the Period Presented (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 8,170
Accumulated Amortization	(7,381)
Net Carrying Value	789	$ 999
Developed technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	3,060
Accumulated Amortization	(3,060)
Net Carrying Value	0
User base and customer relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	5,050
Accumulated Amortization	(4,261)
Net Carrying Value	$ 789
Remaining Useful Life (In Years)	5 years 7 months 6 days
Brand name
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 60
Accumulated Amortization	(60)
Net Carrying Value	$ 0

Goodwill And Other Intangible_5

Goodwill And Other Intangible Assets - Summary of Estimated Amortization of Purchased Intangible Assets (Details) $ in Thousands	Sep. 30, 2019USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2019 (remainder thereof)	$ 70
2020	219
2021	172
2022	136
2023	107
Thereafter	85
Total	$ 789

Other Liabilities (Details)

Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other Liabilities [Abstract]
Loan trailing fee	$ 3,281	$ 3,118
Deferred revenue	297	396
Servicing liabilities	2	12
Deferred income tax liability	392	373
Deferred rent	0	3,408
Restructuring liability	0	2,106
Operating lease liability	18,570
Other	1,023	1,216
Total Other Liabilities	$ 23,565	$ 10,629

Debt (Details)

Debt (Details)		Jun. 20, 2019	Mar. 28, 2019USD ($)	Jun. 12, 2018USD ($)	Jan. 19, 2018USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Line of Credit Facility [Line Items]
Warehouse Lines (1)	[1]					$ 205,818,000	$ 162,488,000
Loans Held for Sale, at Fair Value (1)	[1]					231,644,000	$ 183,788,000
PWIT
Line of Credit Facility [Line Items]
Loans Held for Sale, at Fair Value (1)						124,200,000
PWIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 200,000,000	$ 100,000,000
Repayment period				24 months
Advance rate		89.00%
Commitment fee percent		0.50%
Minimum tangible net worth					25,000,000
Minimum net liquidity					$ 15,000,000
Maximum leverage ratio of 5:1					5
Undrawn portion						89,900,000
Capitalized debt issuance cost						1,800,000
PWIT | Secured Debt
Line of Credit Facility [Line Items]
Warehouse Line						110,100,000
PWIIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 300,000,000
Repayment period			24 months
Advance rate			90.00%
Commitment fee percent			0.50%
Minimum tangible net worth			$ 25,000,000
Minimum net liquidity			$ 15,000,000
Maximum leverage ratio of 5:1			5
Warehouse Line						95,700,000
Loans Held for Sale, at Fair Value (1)						106,000,000
Undrawn portion						204,300,000
Capitalized debt issuance cost						$ 2,100,000
LIBOR | PWIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate		2.90%
LIBOR | PWIIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate			2.90%
Increase to basis spread			0.375%
[1]	(1) Includes amounts in consolidated varia ble interest entities (VIEs) presented separately in the table below.

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income (loss)	$ 10,769	$ (569)	$ (22,714)	$ (19,779)	$ (12,599)	$ (11,401)	$ (12,514)	$ (43,779)
Less: Net Income Allocated to Participating Securities	(7,994)			0			0	0
Net Income (Loss) Attributable to Common Stockholders	$ 2,775			$ (19,779)			$ (12,514)	$ (43,779)
Denominator:
Weighted average shares used in computing net income (loss) per share - basic (in shares)	70,606,805			70,394,269			70,532,641	70,353,819
Effect of dilutive securities:
Stock options	1,939,105			0			0	0
Convertible preferred stock warrants	213,264,845			0			0	0
Weighted average shares used in computing diluted net income (loss) per share - diluted (in shares)	285,810,755			70,394,269			70,532,641	70,353,819
Net income (loss) per share - basic (in shares)	$ 0.04			$ (0.28)			$ (0.18)	$ (0.62)
Net income (loss) per share - diluted (in shares)	$ 0.01			$ (0.28)			$ (0.18)	$ (0.62)

Net Loss Per Share - Common Sto

Net Loss Per Share - Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	502,194,544	496,549,150	502,013,084	498,471,817
Convertible preferred stock issued and outstanding (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	214,637,925	214,637,925	214,637,925	214,637,925
Stock options issued and outstanding (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	73,211,425	67,566,031	73,029,965	69,486,992
Warrants issued and outstanding (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	1,080,349	1,080,349	1,080,349	1,082,055
Series E-1 convertible preferred stock warrants (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	35,544,141	35,544,141	35,544,141	35,544,141
Series F convertible preferred stock warrants (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net loss per common share computation (in shares)	177,720,704	177,720,704	177,720,704	177,720,704

Convertible Preferred Stock, _3

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit - Additional Information (Details) $ / shares in Units, $ in Thousands	Dec. 16, 2016	Feb. 16, 2016	Sep. 30, 2019USD ($)$ / sharesshares	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)time$ / sharesshares	Sep. 30, 2018USD ($)	Dec. 31, 2018$ / sharesshares	Sep. 20, 2017$ / sharesshares	Feb. 27, 2017$ / sharesshares
Class of Stock [Line Items]
Common and preferred stock, shares authorized (in shares)								1,069,760,848
Common stock, shares authorized (in shares)			625,000,000		625,000,000		625,000,000	625,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.01		$ 0.01		$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)			444,760,848		444,760,848		444,760,848	444,760,848
Preferred stock, par value (in dollars per share) | $ / shares								$ 0.01
Common stock, shares issued (in shares)			71,573,501		71,573,501		71,411,145
Common stock, shares outstanding (in shares)			70,637,566		70,637,566		70,475,210
Common Stock
Class of Stock [Line Items]
Stock split conversion ratio of 5-for-1		5
Exercise of stock options (in shares)					162,356
Cash proceeds | $					$ 25
Series B
Class of Stock [Line Items]
IPO value (at least) | $					2,000,000
Aggregate proceeds (at least) | $					$ 100,000
Voting power (at least)					60.00%
Liquidation preference (in dollars per share) | $ / shares			$ 0.60		$ 0.60
Preferred stock, shares authorized (in shares)			35,775,880		35,775,880
Series A-1
Class of Stock [Line Items]
Voting power (at least)					14.00%
Conversion ratio			1,000,000		1,000,000
Liquidation preference (in dollars per share) | $ / shares			$ 2		$ 2
Preferred stock, shares authorized (in shares)			24,760,915		24,760,915
Series D
Class of Stock [Line Items]
Voting power (at least)					60.00%
Liquidation preference (in dollars per share) | $ / shares			$ 6.91		$ 6.91
Series E1 and E2 Preferred Stock
Class of Stock [Line Items]
Voting power (at least)					60.00%
Series G
Class of Stock [Line Items]
Voting power (at least)					60.00%
Conversion ratio			1.36		1.36
Liquidation preference (in dollars per share) | $ / shares			$ 1.34		$ 1.34
Preferred stock, shares authorized (in shares)			37,249,497		37,249,497
Series A
Class of Stock [Line Items]
Conversion ratio			1		1
Times the original issue | time					3
Liquidation preference (in dollars per share) | $ / shares			$ 0.29		$ 0.29
Preferred stock, shares authorized (in shares)			68,558,220		68,558,220
Series C
Class of Stock [Line Items]
Liquidation preference (in dollars per share) | $ / shares			$ 2.87		$ 2.87
Preferred stock, shares authorized (in shares)			24,404,770		24,404,770
Series E-1
Class of Stock [Line Items]
Warrant to purchase (in of shares)									15,277,006
Liquidation preference (in dollars per share) | $ / shares			$ 0.84		$ 0.84
Warrant expiration period	10 years
Income amount | $			$ 1,800	$ 2,100	$ 700	$ 4,600
Preferred stock, shares authorized (in shares)			35,544,141		35,544,141
Series E-2
Class of Stock [Line Items]
Preferred stock, liquidation preference, conversion basis					0.666666666666667
Preferred stock, liquidation preference, conversion basis, after payment					0.333333333333333
Liquidation preference (in dollars per share) | $ / shares			$ 0.84		$ 0.84
Preferred stock, shares authorized (in shares)			16,858,078		16,858,078
Series F
Class of Stock [Line Items]
Exercise price (in dollars per share) | $ / shares									$ 0.01
Voting power (at least)					60.00%
Preferred stock, liquidation preference, conversion basis					0.666666666666667
Preferred stock, liquidation preference, conversion basis, after payment					0.333333333333333
Liquidation preference (in dollars per share) | $ / shares			$ 0.84		$ 0.84
Income amount | $			$ 12,400	$ 7,200	$ 8,100	$ 13,300
Preferred stock, shares authorized (in shares)			177,720,707		177,720,707
Consortium Purchase Agreement | Series F Warrant
Class of Stock [Line Items]
Warrant to purchase (in of shares)									177,720,706
Exercise price (in dollars per share) | $ / shares									$ 0.01

Convertible Preferred Stock, _4

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit - Summary of Shares Authorized, Issued, Outstanding, Par Value and Liquidation Preference of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 20, 2017
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, shares authorized (in shares)	444,760,848	444,760,848	444,760,848
Convertible preferred stock, shares outstanding (in shares)	214,637,925	214,637,925
Convertible preferred stock, shares issued (in shares)	214,637,925	214,637,925
Liquidation Preference (Outstanding Shares)	$ 375,952	$ 375,952
Series A
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	68,558,220
Convertible preferred stock, shares outstanding (in shares)	68,558,220
Convertible preferred stock, shares issued (in shares)	68,558,220
Liquidation Preference (Outstanding Shares)	$ 19,774
Series A-1
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	24,760,915
Convertible preferred stock, shares outstanding (in shares)	24,760,915
Convertible preferred stock, shares issued (in shares)	24,760,915
Liquidation Preference (Outstanding Shares)	$ 49,522
Series B
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	35,775,880
Convertible preferred stock, shares outstanding (in shares)	35,775,880
Convertible preferred stock, shares issued (in shares)	35,775,880
Liquidation Preference (Outstanding Shares)	$ 21,581
Series C
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	24,404,770
Convertible preferred stock, shares outstanding (in shares)	24,404,770
Convertible preferred stock, shares issued (in shares)	24,404,770
Liquidation Preference (Outstanding Shares)	$ 70,075
Series D
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	23,888,640
Convertible preferred stock, shares outstanding (in shares)	23,888,640
Convertible preferred stock, shares issued (in shares)	23,888,640
Liquidation Preference (Outstanding Shares)	$ 165,000
Series E-1
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	35,544,141
Convertible preferred stock, shares outstanding (in shares)	0
Convertible preferred stock, shares issued (in shares)	0
Liquidation Preference (Outstanding Shares)	$ 0
Series E-2
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	16,858,078
Convertible preferred stock, shares outstanding (in shares)	0
Convertible preferred stock, shares issued (in shares)	0
Liquidation Preference (Outstanding Shares)	$ 0
Series F
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	177,720,707
Convertible preferred stock, shares outstanding (in shares)	3
Convertible preferred stock, shares issued (in shares)	3
Liquidation Preference (Outstanding Shares)	$ 0
Series G
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, shares authorized (in shares)	37,249,497
Convertible preferred stock, shares outstanding (in shares)	37,249,497
Convertible preferred stock, shares issued (in shares)	37,249,497
Liquidation Preference (Outstanding Shares)	$ 50,000

Convertible Preferred Stock, _5

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit - Schedule of Assumptions Used (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Volatility | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0.40	0.40
Volatility | Series F
Class of Stock [Line Items]
Fair value assumptions	0.40	0.40
Risk-free interest rate | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0.0163	0.0262
Risk-free interest rate | Series F
Class of Stock [Line Items]
Fair value assumptions	0.0163	0.0263
Remaining contractual term | Series E-1
Class of Stock [Line Items]
Remaining contractual term (in years)	7 years 3 months 14 days	8 years 14 days
Remaining contractual term | Series F
Class of Stock [Line Items]
Remaining contractual term (in years)	7 years 4 months 28 days	8 years 1 month 28 days
Dividend yield | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0	0
Dividend yield | Series F
Class of Stock [Line Items]
Fair value assumptions	0	0

Convertible Preferred Stock, _6

Convertible Preferred Stock, Warrant Liability and Stockholders’ Deficit - Warrant Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Warrants or Rights [Roll Forward]
Change in Fair Value	$ (8,890)	$ (17,885)
Convertible Preferred Stock Warrant
Warrants or Rights [Roll Forward]
Balance at January 1, 2019	143,679	116,366
Warrants Vested	17,553	55,473
Change in Fair Value	(8,890)	(17,885)
Balance at September 30, 2019	$ 152,342	$ 153,954

Share Based Incentive Plan an_3

Share Based Incentive Plan and Compensation - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Financial statement impact amount			$ 3,838,000	$ 6,412,000
Options outstanding, term			7 years 8 months 4 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Unrecognized cost of unvested share-based compensation awards.	$ 0		$ 0
Unamortized expense related to unvested stock-based awards	4,200,000		4,200,000
Internal-use software and website development costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation capitalized	100,000	$ 100,000	300,000	$ 300,000
Stock option repricing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Financial statement impact amount	$ 100,000		$ 300,000
Weighted average vesting period			6 months
Restricted stock units (in shares)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average vesting period			2 years 2 months 12 days
Restricted stock units (in shares) | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
Restricted stock units (in shares) | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years

Share Based Incentive Plan an_4

Share Based Incentive Plan and Compensation - Summarized Option Activity under Option Plan (Details) - 2005 Stock Plan and 2015 Stock Option Plan	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Options Issued and Outstanding
Options Issued and Outstanding, Beginning Balance (in shares) | shares	71,021,698
Options Issued and Outstanding, Options issued (in shares) | shares	8,999,048
Options Issued and Outstanding, Options exercised (in shares) | shares	(162,356)
Options Issued and Outstanding, Options forfeited (in shares) | shares	(4,531,344)
Options Issued and Outstanding, Options expired (in shares) | shares	(53,700)
Options Issued and Outstanding, Ending balance (in shares) | shares	75,273,346
Options Issued and Outstanding, Options vested and expected to vest (in shares) | shares	62,244,684
Options Issued and Outstanding, Options vested and exercisable (in shares) | shares	49,227,760
Weighted- Average Exercise Price
Weighted-Average Exercise Price, Beginning balance (in dollars per share) | $ / shares	$ 0.33
Weighted-Average Exercise Price, Options issued (in dollars per share) | $ / shares	0.28
Weighted-Average Exercise Price, Options exercised (in dollars per share) | $ / shares	0.15
Weighted-Average Exercise Price, Options forfeited (in dollars per share) | $ / shares	0.40
Weighted-Average Exercise Price, Options expired (in dollars per share) | $ / shares	0.30
Weighted-Average Exercise Price, Ending balance (in dollars per share) | $ / shares	0.32
Weighted-Average Exercise Price, Options vested and expected to vest (in dollars per share) | $ / shares	0.32
Weighted-Average Exercise Price, Options vested and exercisable (in dollars per share) | $ / shares	$ 0.28

Share Based Incentive Plan an_5

Share Based Incentive Plan and Compensation - Fair Value of Stock Option Awards (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair value of stock option awards [Abstract]
Volatility of common stock	46.72%	43.76%	46.72%	44.06%
Risk-free interest rate	1.57%	2.85%	2.24%	2.76%
Expected life (in years)	6 years	6 years	5 years 10 months 24 days	6 years
Dividend yield	0.00%	0.00%	0.00%	0.00%

Share Based Incentive Plan an_6

Share Based Incentive Plan and Compensation - Summarized Activities for the Company's RSU's (Details) - Restricted stock units (in shares)	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Number of Shares
Restricted stock unit, Unvested, Beginning Balance (in shares) | shares	4,856,141
Forfeited (in shares) | shares	(53,000)
Restricted stock unit, Unvested, Ending Balance (in shares) | shares	4,803,141
Weighted-Average Grant Date Fair Value
Restricted stock unit, Unvested, Beginning Balance (in dollars per share) | $ / shares	$ 0.96
Forfeited (in dollars per share) | $ / shares	1.90
Restricted stock unit, Unvested, Ending Balance (in dollars per share) | $ / shares	$ 0.95

Share Based Incentive Plan an_7

Share Based Incentive Plan and Compensation - Stock Based Compensation Included in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation	$ 988	$ 1,828	$ 3,838	$ 6,412
Origination and servicing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation	73	213	377	670
Sales and marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation	71	108	216	324
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation	$ 844	$ 1,507	$ 3,245	$ 5,418

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Taxes [Line Items]
Income tax expense	$ 29	$ 8	$ 87	$ 27
Prosper Funding LLC
Income Taxes [Line Items]
Income tax expense			$ 0	$ 0
Net effective tax rate			0.00%

Consortium Purchase Agreement -

Consortium Purchase Agreement - Narrative (Details) - Consortium Purchase Agreement - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2017	Sep. 30, 2019	Dec. 31, 2018	Feb. 27, 2017
Other Commitments [Line Items]
Commitment to purchase borrower loans (up to)		$ 5,000,000		$ 5,000,000
Loans acquired		$ 3,303,283	$ 3,067,332
Amount settled with rebates	$ 300,000
Series F Warrant
Other Commitments [Line Items]
Warrant to purchase up to (in shares)				3
Warrant to purchase (in of shares)				177,720,706
Exercise price (in dollars per share)				$ 0.01

Consortium Purchase Agreement_2

Consortium Purchase Agreement - Consortium Purchase Agreement Table (Details) - Consortium Purchase Agreement - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Other Commitments [Line Items]
Loans Acquired	$ 3,303,283	$ 3,067,332
Loans Purchased by the Consortium	$ 235,951
Series F Warrant
Other Commitments [Line Items]
Warrants Vested (in shares)	177,720,706	154,912,980
Warrants vested during the year (in shares)	22,807,726

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Renewal term		5 years		5 years
Rental expense under operating lease arrangements		$ 1,400	$ 1,000	$ 4,100	$ 3,200
Sublease income		$ 200		600
Minimum sublease rentals						$ 5,300
Right-of-use asset obtained in exchange for operating lease liability	$ 21,600			$ 21,630
Minimum
Lessee, Lease, Description [Line Items]
Operating lease contract term		1 year		1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease contract term		8 years		8 years

Leases - Operating Lease Right-

Leases - Operating Lease Right-of-Use Assets (Details) $ in Thousands	Sep. 30, 2019USD ($)
Lessee, Lease, Description [Line Items]
Gross Carrying Value	$ 16,138
Accumulated Amortization	2,469
Net Carrying Value	13,669
ROU Assets - Office buildings
Lessee, Lease, Description [Line Items]
Gross Carrying Value	15,846
Accumulated Amortization	2,296
Net Carrying Value	13,550
ROU Assets - Other
Lessee, Lease, Description [Line Items]
Gross Carrying Value	292
Accumulated Amortization	173
Net Carrying Value	$ 119

Leases - Schedule of Lease Matu

Leases - Schedule of Lease Maturity (Details) $ in Thousands	Sep. 30, 2019USD ($)
Schedule of Lease Maturity
Remainder of 2019	$ 1,328
2020	5,240
2021	5,134
2022	5,018
2023	1,567
Thereafter	2,546
Total future minimum lease payments	20,833
Less imputed interest	(2,263)
Present value of future minimum lease payments	18,570
Future Minimum Lease Payments
2019	4,536
2020	4,683
2021	4,456
2022	4,319
2023	847
Thereafter	387
Total future operating lease obligations	$ 19,228

Leases - Other Information Rela

Leases - Other Information Related to Leases (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Cash paid for operating leases year-to-date		$ 3,903
Right-of-use asset obtained in exchange for operating lease liability	$ 21,600		$ 21,630
Weighted average remaining lease term		4 years 3 months 21 days	4 years 3 months 21 days
Weighted average discount rate		5.53%	5.53%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	Apr. 19, 2019	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Commitments And Contingencies [Line Items]
Designated Amount for loans (less than)			$ 143,500	$ 143,500
Minimum fee, remaining in current year			400,000	400,000
Minimum fee, years two and three			1,700,000
Minimum fee, year four			100,000
Minimum liquidity covenant			15,000,000	15,000,000
Purchase of borrower loans			33,400,000
Maximum potential future payments			3,800,000,000	3,800,000,000
Accrued repurchase and indemnification obligation			1,000,000	1,000,000	$ 900,000
Amount awarded to other party	$ 3,000,000
Accrued penalty		$ 3,000,000
Prosper Funding LLC
Commitments And Contingencies [Line Items]
Designated Amount for loans (less than)			143,500	143,500
Minimum fee, remaining in current year			400,000	400,000
Minimum fee, years two and three			1,700,000
Minimum fee, year four			100,000
Minimum liquidity covenant			15,000,000	15,000,000
Purchase of borrower loans				33,400,000
Maximum potential future payments			3,800,000,000	3,800,000,000
Accrued repurchase and indemnification obligation			1,000,000	$ 1,000,000	$ 900,000
Amount awarded to other party	$ 3,000,000
Accrued penalty			$ 3,000,000

Related Parties - Additional In

Related Parties - Additional Information (Details)	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Minimum percentage of voting securities considered for related parties	10.00%
Minimum percentage of stockholders considered for related parties	10.00%

Related Parties - Aggregate Amo

Related Parties - Aggregate Amount of Notes Purchased and the Income Earned (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	$ 107	$ 110	$ 326	$ 327
Interest Earned on Notes and Borrower Loans	14	11	41	34
Notes balance	653		653		$ 601
Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	6	3	17	12
Interest Earned on Notes and Borrower Loans	1	0	4	1
Notes balance	35		35		32
Executive officers and management
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	6	3	17	12
Interest Earned on Notes and Borrower Loans	1	0	4	1
Notes balance	35		35		32
Executive officers and management | Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	6	3	17	12
Interest Earned on Notes and Borrower Loans	1	0	4	1
Notes balance	35		35		32
Directors (excluding executive officers and management)
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	101	107	309	315
Interest Earned on Notes and Borrower Loans	13	11	37	33
Notes balance	618		618		569
Directors (excluding executive officers and management) | Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes and Borrower Loans Purchased	0	0	0	0
Interest Earned on Notes and Borrower Loans	0	$ 0	0	$ 0
Notes balance	$ 0		$ 0		$ 0

Significant Concentrations (Det

Significant Concentrations (Details)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Concentration Risk [Line Items]
Percentage of funds originating in channel	93.00%	93.00%
Party One
Concentration Risk [Line Items]
Percentage of loan purchased	11.00%	52.00%