Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating Activities
Net income (loss)	$ (23,762)	$ (22,893)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	3,539	2,935
Stock-based compensation.	5,320	3,734
Change in assets and liabilities:
Restricted cash	(8,032)	(8,610)
Prepaid expenses	1,842	4,523
Accrued revenue	(3,885)	(7,168)
Other current assets	6,482	(10)
Other long-term assets	377	(5,816)
Accounts payable	901	332
Accrued expenses	8,481	5,859
Other payables	7,814	8,609
Deferred lease liability	1,097	(157)
Origination of loans held for sale	(3,022)	0
Proceeds from sale of loans originated as held for sale	2,477	0
Net cash used in operating activities	(371)	(18,662)
Investing activities
Maturities of short-term investments	1,239	1,644
Purchases of short-term investments	(992)	(1,644)
Purchases of property and equipment	(9,435)	(2,660)
Net cash used in investing activities	(9,188)	(2,660)
Financing activities
Proceeds from exercise of stock options	1,017	462
Payment of deferred initial public offering costs	(1,807)	0
Borrowings from warehouse credit facilities	2,932	0
Repayments of warehouse credit facilities	(2,403)	0
Net cash provided by (used in) financing activities	(261)	462
Net change in cash and cash equivalents	(9,820)	(20,860)
Cash and cash equivalents:
Beginning of period	64,030	85,597
End of period	54,210	64,737
Supplemental disclosure of non-cash investing and financing activities
Accretion of redeemable convertible preferred stock	(135,690)	59,869
Stock-based compensation capitalized in property and equipment	(131)	(39)
Deferred initial public offering cost accruals	(343)	0
Leasehold improvements paid directly by lessor	$ (104)	$ 0