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Schedule II - Valuation And Qualifying Accounts And Reserves Valuation and Qualifying Accounts and Reserves (Tables)
 12 Months Ended
Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]  
Summary of Valuation Allowance [Table Text Block]
Allowance for Doubtful Accounts:
Description
Balance at
Beginning
of Period
Additions
Charged to
Costs &
Expenses
Deductions
& Net
Write-Offs
Balance at
End of
Period
 (In thousands)
Year ended December 31, 2019$2,531  $527  $(726) $2,332  
Year ended December 31, 2018$2,450  $81  $—  $2,531  
Year ended December 31, 2017$3,773  $348  $(1,671) $2,450