Variable Interest Entities - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Variable Interest Entity [Line Items]
Total revenue	$ 105,704	$ 82,420	$ 191,030	$ 147,757
Total operating expenses	58,896	45,081	120,645	88,826
Operating profit	46,808	37,339	70,385	58,931
Total other income/(expense), net	(4,398)	$ 1,254	(9,371)	$ 1,673
Net income attributable to GreenSky, Inc.	5,550		5,550
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total revenue	105,704		191,030
Total operating expenses	58,896		120,645
Operating profit	46,808		70,385
Total other income/(expense), net	(4,398)		(9,371)
Net income attributable to GreenSky, Inc.	$ 42,410		$ 61,014