Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income (loss)	$ (14,345)	$ (85,482)	$ (2,231)
Adjustments to reconcile net loss to net cash provided by operating activities:
Provision for loan losses	152,926	149,963	74,863
Depreciation and amortization	9,951	9,462	6,508
Amortization of debt issuance costs	3,806	4,538	2,837
Stock-based compensation	12,515	15,915	11,582
Amortization of net deferred origination costs	48,219	36,040	32,939
Changes in servicing rights, at fair value	2,097	4,997	1,270
Gain on sales of loans	(2,485)	(14,411)	(53,354)
Unfunded loan commitment reserve	535	(307)	2,922
Gain on extinguishment of debt	(312)	(1,372)	(421)
Changes in operating assets and liabilities:
Other assets	4,768	(1,942)	(12,269)
Accounts payable	(2,597)	2,570	236
Interest payable	208	1,365	(62)
Accrued expenses and other liabilities	(6,206)	5,580	16,034
Originations of loans held for sale	(49,813)	(304,258)	(445,968)
Capitalized net deferred origination costs of loans held for sale	(1,667)	(10,269)	(17,601)
Proceeds from sale of loans held for sale	51,463	314,627	489,364
Principal repayments of loans held for sale	1,135	7,235	12,298
Net cash provided by operating activities	210,198	134,251	118,947
Cash flows from investing activities
Change in restricted cash	970	(5,969)	(9,015)
Purchases of property, equipment and software	(1,340)	(6,640)	(13,692)
Capitalized internal-use software	(2,919)	(4,645)	(4,197)
Originations of term loans and lines of credit, excluding rollovers into new originations	(1,758,600)	(1,826,085)	(1,162,537)
Proceeds from sale of loans held for investment	24,826	75,787	177,014
Payments of net deferred origination costs	(44,778)	(47,082)	(28,353)
Principal repayments of term loans and lines of credit	1,639,117	1,232,272	872,551
Other	0	(201)	(186)
Purchase of loans	(13,840)	(6,671)	0
Net cash used in investing activities	(156,564)	(589,234)	(168,415)
Cash flows from financing activities
Investments by noncontrolling interests	3,443	0	7,873
Purchase of treasury shares	(1,268)	(855)	0
Proceeds from exercise of stock options and warrants	454	197	251
Payments of initial public offering costs	0	0	(1,845)
Redemption of common stock and warrants	0	0	(187)
Issuance of common stock under employee stock purchase plan	1,838	2,606	1,825
Payments of debt issuance costs	(4,108)	(6,281)	(1,690)
Distribution to noncontrolling interest	(957)	0	0
Net cash provided by (used in) financing activities	(62,496)	374,728	(10,468)
Effect of exchange rate changes on cash and cash equivalents	670	(13)	(675)
Net increase (decrease) in cash and cash equivalents	(8,192)	(80,268)	(60,611)
Cash and cash equivalents at beginning of year	79,554	159,822	220,433
Cash and cash equivalents at end of year	71,362	79,554	159,822
Supplemental disclosure of other cash flow information
Cash paid for interest	41,918	24,778	15,394
Supplemental disclosures of non-cash investing and financing activities
Loans transferred from loans held for sale to loans held for investment	0	884	1,348
Stock-based compensation included in capitalized internal-use software	175	1,470	877
Unpaid principal balance of term loans rolled into new originations	306,250	273,453	265,933
Funding debt
Cash flows from financing activities
Proceeds from the issuance of debt	177,581	752,443	212,562
Repayment of debt	(219,479)	(398,682)	(219,957)
Corporate debt
Cash flows from financing activities
Proceeds from the issuance of debt	34,200	25,300	2,700
Repayment of debt	$ (54,200)	$ 0	$ (12,000)