XML 66 R40.htm IDEA: XBRL DOCUMENT
v3.20.4

Activity in Company's Allowance for Doubtful Accounts (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Balance at Beginning of Period |  | $ 1.0 | $ 1.3 | $ 1.6
Provision |  | 5.5 | 4.9 | 6.0
Recoveries |  | 0.6 | 0.8 | 0.6
Accounts Written Off |  | 4.4 | 6.0 | 6.9
Regulatory Defferals | [1] | 0.6 |  |
Balance at End of Period |  | 3.3 | 1.0 | 1.3
Electric |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Balance at Beginning of Period |  | 0.6 | 0.5 | 0.9
Provision |  | 2.9 | 3.0 | 3.2
Recoveries |  | 0.3 | 0.3 | 0.3
Accounts Written Off |  | 2.6 | 3.2 | 3.9
Regulatory Defferals | [1] | 0.4 |  |
Balance at End of Period |  | 1.6 | 0.6 | 0.5
Gas |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Balance at Beginning of Period |  | 0.4 | 0.8 | 0.6
Provision |  | 2.6 | 1.9 | 2.9
Recoveries |  | 0.3 | 0.5 | 0.3
Accounts Written Off |  | 1.8 | 2.8 | 3.0
Regulatory Defferals | [1] | 0.2 |  |
Balance at End of Period |  | $ 1.7 | $ 0.4 | 0.8
Others |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Balance at Beginning of Period |  |  |  | 0.1
Provision |  |  |  | $ (0.1)
[1] | The Company has incurred greater than normal bad debt expense due to the coronavirus pandemic. Incremental bad debt expense amounts have been deferred as regulatory assets based on certain regulatory proceedings and management’s belief that such amounts are probable of recovery (See the “Financial Effects of COVID-19 Pandemic” section in Note 8 (Commitments and Contingencies). The Company will track the collection of receivables and to the extent incremental bad debt amounts are collected in the future, such amounts will reduce the regulatory assets recorded.

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of allowance for credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase in allowance for credit loss on accounts receivable, from recovery. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of direct write-downs of accounts receivable charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expense (reversal of expense) for expected credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(5)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_ProvisionForDoubtfulAccounts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Accounts receivable allowance for credit losses provisions for bad debts deferred due to regulatory need. + References No definition available. + Details
Name: | utl_AccountsReceivableAllowanceForCreditLossesProvisionsForBadDebtsDeferredDueToRegulatoryNeed
Namespace Prefix: | utl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | utl_InvestmentHoldingsAxis=utl_ElectricMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | utl_InvestmentHoldingsAxis=utl_GasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | utl_InvestmentHoldingsAxis=utl_OthersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |