Fair Value of Assets and Liabilities - Servicing liabilities and unobservable inputs (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Servicing Liability at Fair Value, Amount
Beginning balance	$ 2,187	$ 2,071
Initial obligation from transfer of Charged-Off Receivables	450	911
Change in inputs or assumptions used in the valuation model	0	0
Other changes in fair value	(365)	(710)
Ending balance	$ 2,272	$ 2,272	$ 2,071
Servicing Liabilities at Fair Value [Line Items]
Cost of servicing (basis points)		0.625%	0.625%
Discount rate		18.00%	18.00%
Weighted Average
Servicing Liabilities at Fair Value [Line Items]
Cost of servicing (basis points)		0.625%	0.625%
Discount rate		18.00%	18.00%
Recovery period		4 years 4 months 24 days	4 years 9 months 18 days
Minimum
Servicing Liabilities at Fair Value [Line Items]
Recovery period		4 years 1 month 6 days	4 years 7 months 6 days
Maximum
Servicing Liabilities at Fair Value [Line Items]
Recovery period		4 years 10 months 24 days	4 years 10 months 24 days

Servicing Assets And Servicing Liabilities At Fair Value, Assumptions Used To Estimate Fair Value, Cost Of Servicing

No definition available.

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- Definition

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
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- Definition

Weighted average life of financial assets and financial liabilities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The value of new servicing liabilities, that are subsequently measured at fair value, acquired or created during the current period through assumptions of servicing obligations and servicing obligations that result from transfers of financial assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Fair value of a liability representing servicing arrangements under which the estimated future revenue from contractually specified servicing fees, late charges, and other ancillary revenues are not expected to adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of increase (decrease) in fair value from changes in the inputs, assumptions, or model used to calculate the fair value of the contract to service financial assets under which the estimated future revenues from contractually specified servicing fees, late charges, and other ancillary revenues are not expected to adequately compensate the servicer.

+ References

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- Definition

Amount of increase (decrease) from changes in fair value classified as other for a contract to service financial assets under which the estimated future revenues from contractually specified servicing fees, late charges, and other ancillary revenues are not expected to adequately compensate the servicer.

+ References

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