Securities Available for Sale - Amortized cost/fair value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 245,083		$ 271,173
Gross Unrealized Gains	374		1,078
Gross Unrealized Losses	(7,956)		(1,324)
Allowance for Credit Losses	(15,571)	$ (18,835)	0
Fair Value	221,930		270,927
Asset-backed senior securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,300		108,780
Gross Unrealized Gains	5		597
Gross Unrealized Losses	(3,689)		(38)
Allowance for Credit Losses	0
Fair Value	94,616		109,339
Securities pledged as collateral at fair value	148,800		174,800
CLUB Certificate asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	86,000		90,728
Gross Unrealized Gains	79		41
Gross Unrealized Losses	(2,858)		(1,063)
Allowance for Credit Losses	(6,587)	(8,638)	0
Fair Value	76,634		89,706
Asset-backed subordinated securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	29,106		20,888
Gross Unrealized Gains	243		423
Gross Unrealized Losses	(1,409)		(221)
Allowance for Credit Losses	(8,984)	$ (10,197)	0
Fair Value	18,956		21,090
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,502		14,333
Gross Unrealized Gains	30		11
Gross Unrealized Losses	0		(1)
Allowance for Credit Losses	0
Fair Value	8,532		14,343
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,293		9,274
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0
Fair Value	8,293		9,274
Other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,182		12,075
Gross Unrealized Gains	17		6
Gross Unrealized Losses	0		(1)
Allowance for Credit Losses	0
Fair Value	8,199		12,080
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,700		13,100
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0
Fair Value	6,700		13,100
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost			1,995
Gross Unrealized Gains			0
Gross Unrealized Losses			0
Fair Value			1,995
Asset-backed securities, securitized loans and receivables, subject to restrictions on transfer
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 173,800		$ 219,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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