XML 28 R35.htm IDEA: XBRL DOCUMENT v3.20.1

Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Dividends Payable [Line Items]
Dividend Amount	$ 0.375	$ 0.370
Group One
Dividends Payable [Line Items]
Declaration Date	Apr. 29, 2020
Date Paid (Payable)	May 29, 2020
Shareholder of Record Date	May 15, 2020
Dividend Amount	$ 0.375
Group Two
Dividends Payable [Line Items]
Declaration Date	Jan. 29, 2020
Date Paid (Payable)	Feb. 28, 2020
Shareholder of Record Date	Feb. 14, 2020
Dividend Amount	$ 0.375
Group Three
Dividends Payable [Line Items]
Declaration Date	Oct. 23, 2019
Date Paid (Payable)	Nov. 27, 2019
Shareholder of Record Date	Nov. 13, 2019
Dividend Amount	$ 0.370
Group Four
Dividends Payable [Line Items]
Declaration Date	Jul. 24, 2019
Date Paid (Payable)	Aug. 29, 2019
Shareholder of Record Date	Aug. 15, 2019
Dividend Amount	$ 0.370
Group Five
Dividends Payable [Line Items]
Declaration Date	Apr. 24, 2019
Date Paid (Payable)	May 29, 2019
Shareholder of Record Date	May 15, 2019
Dividend Amount	$ 0.370
Group Six
Dividends Payable [Line Items]
Declaration Date	Jan. 30, 2019
Date Paid (Payable)	Feb. 28, 2019
Shareholder of Record Date	Feb. 14, 2019
Dividend Amount	$ 0.370

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 http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Date the declared dividend will be paid, in CCYY-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 http://asc.fasb.org/extlink&oid=98513485&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 CCYY-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 http://asc.fasb.org/extlink&oid=98513485&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 CCYY-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: