Annual report pursuant to Section 13 and 15(d)

Borrowings - Fair Value (Narrative) (Details)

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Borrowings - Fair Value (Narrative) (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Long-term line of credit $ 100 $ 10,000
Notes payable to bank | Long-term mortgage notes and bonds payable    
Debt Instrument [Line Items]    
Long-term debt, fair value 328,500  
Secured debt 338,100  
Notes payable to bank | Short-term mortgage notes and bonds payable    
Debt Instrument [Line Items]    
Long-term line of credit $ 100