Fair Value Of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivable	$ 35,406
Carrying Amount [Member] | Fixed-Rate Term Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	153,500	$ 158,600
Carrying Amount [Member] | Collateralized Financing Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	115,400	107,200
Carrying Amount [Member] | Senior Secured Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	55,800	58,900
Carrying Amount [Member] | Asset Backed Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	965,400	1,032,700
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivable	35,400
Fair Value [Member] | Fixed-Rate Term Loans [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	154,800
Fair Value [Member] | Collateralized Financing Obligations [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	117,300	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	972,500	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	$ 39,000	$ 1,500