Leases (Components Of Net Investment In Direct Finance Leases) (Details)		12 Months Ended
		Dec. 31, 2020 USD ($) customer	Dec. 31, 2019 USD ($) customer
Gross finance lease receivables	[1]	$ 909,727,000	$ 804,880,000
Unearned income	[2]	(280,116,000)	(238,164,000)
Net investment in finance leases		629,611,000	566,716,000
Allowance for credit losses		(46,000)
Net investment in finance leases, net of allowance for credit losses		629,565,000	566,716,000
Unguaranteed residual value		98,200,000	74,300,000
Executory costs		0	0
Unamortized initial direct costs		$ 0	$ 0
Finance Lease [Member] | Customer Concentration Risk [Member]
Number of major customers | customer		1	1
Concentration percentage		75.00%	65.00%

[1] At the inception of the lease, the Company records the total minimum lease payments, executory costs, if any, and unguaranteed residual value as gross finance lease receivables. The gross finance lease receivables are reduced as customer payments are received. There was $98.2 million and $74.3 million unguaranteed residual value at December 31, 2020 and 2019, respectively, included in gross finance lease receivables. There were no executory costs included in gross finance lease receivables as of December 31, 2020 and 2019.

[2] The difference between the gross finance lease receivables and the cost of the equipment or carrying amount at the lease inception is recorded as unearned income. Unearned income, together with initial direct costs, are amortized to income over the lease term so as to produce a constant periodic rate of return. There were no unamortized initial direct costs as of December 31, 2020 and 2019.