Debt And Derivative Instruments (Narrative) (Details) - USD ($)			3 Months Ended	9 Months Ended
		Sep. 25, 2020	Sep. 30, 2020	Sep. 30, 2020	Sep. 09, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Restricted cash			$ 316,915,000	$ 316,915,000
Derivative, Maturity Date			Jun. 30, 2025
Amount expected to be reclassified in the next twelve months			$ 400,000	400,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Maturity Date			Jun. 30, 2025
Derivative amount			$ 500,000,000.0	$ 500,000,000.0		$ 0
Derivative, Fixed Interest Rate			0.29%	0.29%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum credit commitment			$ 464,200,000	$ 464,200,000
Available borrowing capacity			164,100,000	$ 164,100,000
Debt instrument maturity date	[1]			Jun. 01, 2023
Revolving Credit Facility [Member] | Consortium of Banks [Member]
Debt Instrument [Line Items]
Letters of credit outstanding			$ 100,000	$ 100,000
Asset Backed Notes [Member]
Debt Instrument [Line Items]
Outstanding balance repaid		$ 742,500,000
Asset Backed Notes [Member] | CAL Funding IV Limited [Member]
Debt Instrument [Line Items]
Date of first required payment				Oct. 26, 2020
Debt instrument maturity date				Mar. 27, 2028
Asset Backed Notes [Member] | Class A Asset-Backed Notes [Member] | CAL Funding IV Limited [Member]
Debt Instrument [Line Items]
Principal amount of loan					$ 715,900,000
Fixed interest rate					2.20%
Asset Backed Notes [Member] | Class B Asset-Backed Notes [Member] | CAL Funding IV Limited [Member]
Debt Instrument [Line Items]
Principal amount of loan					$ 26,800,000
Fixed interest rate					3.50%

[1] $500 million of this outstanding debt is subject to an interest rate swap at a cost of 0.29% as described below in Derivative Instruments.