XML 51 R37.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Schedule II - Valuation and Qualifying Accounts (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] |
Valuation and qualifying accounts |
Description |  | Balance at Beginning of Period |  | Additions - Charged to Costs and Expenses |  | Additions - Charged to Other Accounts - Describe |  | Deductions - Describe |  | Balance at End of Period
Allowance for doubtful accounts: |  |  |  |  |  |  |  |  |  |  |
For the year ended December 31, 2018 |  | $ | 12,717 |  |  | $ | 9,475 |  |  | $ | — |  |  | $ | 8,954 |  | (1) |  | $ | 13,238 |
For the year ended December 31, 2017 |  | 12,040 |  |  | 8,598 |  |  | — |  |  | 7,921 |  | (1) |  | 12,717 |
For the year ended December 31, 2016 |  | $ | 9,637 |  |  | $ | 9,587 |  |  | $ | — |  |  | $ | 7,184 |  | (1) |  | $ | 12,040 |
(1) | Uncollectable accounts written off.

X
- References No definition available. + Details
Name: | srt_ValuationAndQualifyingAccountsAbstract
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of credit losses for current financing receivables (such as trade and accounts receivable), including a rollforward of the balance. An alternative caption includes allowance for doubtful accounts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
Name: | us-gaap_ScheduleOfCreditLossesForFinancingReceivablesCurrentTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration