Variable Interest Entities - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Assets
Cash	$ 236,629	$ 224,614	$ 107,087
Restricted cash	142,542	129,224	103,569
Loan receivables held for sale, net	43,489	73,606	$ 82,250	$ 41,268
Accounts receivable, net	20,424	18,358
Related party receivables	335	218
Property, equipment and software, net	8,518	7,848
Other assets	5,401	9,021
Total assets	758,696	462,889
Liabilities
Accounts payable	6,342	6,845
Accrued compensation and benefits	6,451	7,677
Other accrued expenses	1,077	1,606
Finance charge reversal liability	107,047	94,148
Term loan	387,979	338,263
Related party liabilities	825	1,548
Other liabilities	39,612	38,841
Total liabilities	805,156	488,928
Permanent Equity (Deficit)
Total permanent equity (deficit)	(46,460)
Total liabilities, temporary and permanent equity (deficit)	758,696	$ 462,889
Variable Interest Entity, Primary Beneficiary
Assets
Cash	236,524
Restricted cash	142,542
Loan receivables held for sale, net	43,489
Accounts receivable, net	20,424
Related party receivables	335
Property, equipment and software, net	8,518
Other assets	5,401
Total assets	457,233
Liabilities
Accounts payable	6,342
Accrued compensation and benefits	6,451
Other accrued expenses	1,077
Finance charge reversal liability	107,047
Term loan	387,979
Related party liabilities	825
Other liabilities	39,612
Total liabilities	549,333
Permanent Equity (Deficit)
Noncontrolling interest	(68,020)
Total permanent equity (deficit)	(24,080)
Total permanent equity (deficit)	(92,100)
Total liabilities, temporary and permanent equity (deficit)	$ 457,233