001 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS link:presentationLink link:definitionLink link:calculationLink 002 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) link:presentationLink link:definitionLink link:calculationLink 003 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND RETAINED EARNINGS link:presentationLink link:definitionLink link:calculationLink 004 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME link:presentationLink link:definitionLink link:calculationLink 005 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parentheticals) link:presentationLink link:definitionLink link:calculationLink 006 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:definitionLink link:calculationLink 007 - Disclosure - Accounting Records and Use of Estimates link:presentationLink link:definitionLink link:calculationLink 008 - Disclosure - Income Per Share of Common Stock link:presentationLink link:definitionLink link:calculationLink 009 - Disclosure - Comprehensive Income link:presentationLink link:definitionLink link:calculationLink 010 - Disclosure - Marketable Securities link:presentationLink link:definitionLink link:calculationLink 011 - Disclosure - Financial Instruments and Credit Risk Concentrations link:presentationLink link:definitionLink link:calculationLink 012 - Disclosure - Long-Term Debt - Mortgages and Term Loan link:presentationLink link:definitionLink link:calculationLink 013 - Disclosure - Property and Equipment - at cost link:presentationLink link:definitionLink link:calculationLink 014 - Disclosure - Note Payable link:presentationLink link:definitionLink link:calculationLink 015 - Disclosure - Unbilled Receivables and Rental Income link:presentationLink link:definitionLink link:calculationLink 016 - Disclosure - Employees' Retirement Plan link:presentationLink link:definitionLink link:calculationLink 017 - Disclosure - Cash Flow Information link:presentationLink link:definitionLink link:calculationLink 018 - Disclosure - Capitalization link:presentationLink link:definitionLink link:calculationLink 019 - Disclosure - Contingencies link:presentationLink link:definitionLink link:calculationLink 000 - Disclosure - Document And Entity Information link:presentationLink link:definitionLink link:calculationLink