Income Taxes (Schedule Of Additional Information Related To Unrecognized Uncertain Tax Positions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits on uncertain tax positions (reflected in current income tax, other noncurrent liability accounts, or deferred tax assets in the balance sheet)	$ 881	$ 3,361	$ 1,962	$ 3,315
Deferred income tax assets related to unrecognized tax benefits on uncertain tax positions (reflected in deferred income tax accounts in the balance sheet)	(163)	(211)	(153)
Net unrecognized tax benefits on uncertain tax positions, which would impact the effective tax rate if recognized	718	3,150	1,809
Interest and penalties accrued on deductions taken relating to uncertain tax positions (approximately $(144), $107 and $(1) reflected in income tax expense in the income statement in 2019, 2018 and 2017, respectively, with the balance shown in current income tax and other noncurrent liability accounts in the balance sheet)	100	243	136
Interest and penalties accrued on deductions taken relating to uncertain tax positions, reflected in income tax expense in the income statement	(144)	107	(1)
Related deferred income tax assets recognized on interest and penalties	(23)	(56)	(32)
Interest and penalties accrued on uncertain tax positions net of related deferred income tax benefits, which would impact the effective tax rate if recognized	77	187	104
Total net unrecognized tax benefits on uncertain tax positions reflected in the balance sheet, which would impact the effective tax rate if recognized	$ 795	$ 3,337	$ 1,913