Fair Value Of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivable	$ 35,314
Carrying Amount [Member] | Fixed-Rate Term Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	151,000	$ 158,600
Carrying Amount [Member] | Collateralized Financing Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	99,400	107,200
Carrying Amount [Member] | Senior Secured Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	52,800	58,900
Carrying Amount [Member] | Asset Backed Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	931,800	1,032,700
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivable	35,300
Fair Value [Member] | Fixed-Rate Term Loans [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	153,700
Fair Value [Member] | Collateralized Financing Obligations [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	100,800	108,900
Fair Value [Member] | Asset Backed Notes [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	945,300	1,024,700
Variable Interest Entity, Primary Beneficiary [Member] | Carrying Amount [Member] | Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 37,800	$ 1,500