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VALUATION AND QUALIFYING ACCOUNTS
 12 Months Ended
Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]  
VALUATION AND QUALIFYING ACCOUNTS
SCHEDULE II
SPOK HOLDINGS, INC.
VALUATION AND QUALIFYING ACCOUNTS
 
Allowance for Doubtful Accounts,
Service Credits and Other
 
Balance at the
Beginning of
the Period
 
Charged to
Operations
 
Write-offs
 
Balance at the
End of the
Period
 
 
(Dollars in thousands)
Year ended December 31, 2018
 
$
1,065

 
$
2,125

 
$
(1,485
)
 
$
1,705

Year ended December 31, 2017
 
$
1,056

 
$
1,035

 
$
(1,026
)
 
$
1,065

Year ended December 31, 2016
 
$
1,286

 
$
761

 
$
(991
)
 
$
1,056