XML 49 R37.htm IDEA: XBRL DOCUMENT
v3.23.1

Dividends Declared Per Share (Detail) - $ / shares | 3 Months Ended
--- | ---
Mar. 31, 2023 | Mar. 31, 2022
Dividends Payable [Line Items] |  |
Dividend Amount | $ 0.405 | $ 0.39
Group One |  |
Dividends Payable [Line Items] |  |
Declaration Date | Apr. 26, 2023 |
Date Paid (Payable) | May 30, 2023 |
Shareholder of Record Date | May 15, 2023 |
Dividend Amount | $ 0.405 |
Group Two |  |
Dividends Payable [Line Items] |  |
Declaration Date | Jan. 25, 2023 |
Date Paid (Payable) | Feb. 28, 2023 |
Shareholder of Record Date | Feb. 14, 2023 |
Dividend Amount | $ 0.405 |
Group Three |  |
Dividends Payable [Line Items] |  |
Declaration Date | Oct. 26, 2022 |
Date Paid (Payable) | Nov. 28, 2022 |
Shareholder of Record Date | Nov. 14, 2022 |
Dividend Amount | $ 0.390 |
Group Four |  |
Dividends Payable [Line Items] |  |
Declaration Date | Jul. 27, 2022 |
Date Paid (Payable) | Aug. 26, 2022 |
Shareholder of Record Date | Aug. 12, 2022 |
Dividend Amount | $ 0.390 |
Group Five |  |
Dividends Payable [Line Items] |  |
Declaration Date | Apr. 27, 2022 |
Date Paid (Payable) | May 27, 2022 |
Shareholder of Record Date | May 13, 2022 |
Dividend Amount | $ 0.390 |
Group Six |  |
Dividends Payable [Line Items] |  |
Declaration Date | Jan. 26, 2022 |
Date Paid (Payable) | Feb. 25, 2022 |
Shareholder of Record Date | Feb. 11, 2022 |
Dividend Amount | $ 0.390 |

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the declared dividend will be paid, in YYYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the dividend to be paid was declared, in YYYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the holder must own the stock to be entitled to the dividend, in YYYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

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_DividendsPayableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=utl_GroupSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |