SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS - Allowance for Doubtful Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Movement in Valuation Allowances and Reserves | |||
| Balance at Beginning of Period | $ 22,398 | $ 25,348 | $ 24,308 |
| Charges to Costs, Expenses and other | 6,740 | 10,659 | 13,384 |
| Write-off of Accounts Receivable | 8,057 | 13,069 | 10,585 |
| Other | 1,406 | (540) | (1,759) |
| Balance at End of Period | $ 22,487 | $ 22,398 | $ 25,348 |