XML 24 R9.htm IDEA: XBRL DOCUMENT
v3.3.1.900

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY [Abstract] |  |
Conversion of Convertible Preferred Stock Value Per Share | $ 7.00 | $ 8.00

X
- Definition Refers to per share value of conversion of convertible preferred stock. + References No definition available. + Details
Name: | msex_ConversionOfConvertiblePreferredStockValuePerShare
Namespace Prefix: | msex_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

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