Financial Instruments (Estimated Fair Values of Financial Instruments) (Parenthetical) (Details) |
Dec. 31, 2018
USD ($)
|
---|---|
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] | |
Liabilities held for sale | $ 29,321,000 |
Revenue bonds [Member] | |
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] | |
Liabilities held for sale | $ 29,000 |