XML 18 R28.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Short-term Borrowings (Schedule of Short Term Borrowings) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Lines Of Credit Facility |  |  |  |
Weighted daily outstanding amount | $ 28,832 | $ 28,608 | $ 27,906 | $ 27,472
Weighted average interest rates | 1.44% | 1.32% | 1.44% | 1.35%

X
- Definition Weighted average interest rate of average daily amounts of credit lines. + References No definition available. + Details
Name: | msex_ShortTermDebtWeightedAverageInterestRate1
Namespace Prefix: | msex_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LineOfCreditFacilityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average amount borrowed under the credit facility during the period. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityAverageOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration