Other Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Machinery and Equipment, Gross	$ 10,432	$ 8,459
Furniture and Fixtures, Gross	10,768	9,542
Other Purchased Software, Gross	4,527	3,955
Property, Plant and Equipment, Other, Gross	171	842
Leasehold Improvements, Gross	27,701	23,006
Property, Plant and Equipment, Gross	53,599	45,804
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(30,765)	(22,609)
Property, Plant and Equipment, Net	22,834	23,195
Capitalized Computer Software, Gross	36,795	19,022
Capitalized Computer Software, Accumulated Amortization	(18,456)	(13,530)
Capitalized Computer Software, Net	18,339	5,492
Income Taxes Receivable	13,107	24,597
Accounts Receivable from Securitization	6,621	5,769
Prepaid Expense	12,217	9,237
Deferred IPO Costs	0	3,211
Other Assets, Miscellaneous	2,090	1,797
Other Assets	75,208	73,298
Depreciation	8,800	8,300	$ 7,500
Capitalized Computer Software, Amortization	4,900	3,500	3,100
Capitalized Computer Software, Additions	$ 17,900	$ 3,300	$ 3,500