Income Taxes (Schedule Of Effective Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	21.00%
Income subject to tonnage tax	(7.30%)	(2.30%)	(1.30%)
U.S. federal income tax statutory changes	(49.10%)	0.00%	0.00%
Non-deductible expenses	3.40%	1.60%	0.20%
Noncontrolling interests	0.00%	(3.10%)	(5.70%)
Foreign earnings not subject to U.S. income tax	(4.80%)	(4.10%)	(16.20%)
Foreign taxes not creditable against U.S. income tax	0.20%	1.40%	3.20%
Subpart F income	3.00%	1.50%	12.10%
State taxes	5.90%	2.00%	(3.10%)
Share award plans	1.60%	0.60%	(0.30%)
Other	(0.90%)	1.40%	(0.70%)
Effective income tax rate	(27.00%)	20.00%	9.20%