Long-Term Debt (Schedule of Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Jun. 05, 2019
Debt Instrument [Line Items]
Debt issuance costs	$ (13,800)	$ (11,800)
Long-term debt, net of debt issuance costs	1,506,200	1,288,200
Current portion of long-term debt	0	0
Long-term debt	$ 1,506,203	$ 1,288,248
Series 2019-1 4.194% Fixed Rate Senior Secured Notes, Class A-2-I
Debt Instrument [Line Items]
Debt interest rate (percent)	4.194%	4.194%	4.194%
Senior notes	$ 700,000	$ 700,000
Series 2019-1 4.723% Fixed Rate Senior Secured Notes, Class A-2-II
Debt Instrument [Line Items]
Debt interest rate (percent)	4.723%	4.723%
Senior notes	$ 600,000	$ 600,000
Series 2019-1 Variable Funding Senior Notes Class A-1, variable interest rate of 3.39% at March 31, 2020
Debt Instrument [Line Items]
Debt interest rate (percent)	3.39%
Senior notes	$ 220,000
Debt issuance costs	$ (13,800)

Contractual interest rate for funds borrowed, under the debt agreement.

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