Lines of Credit Lines of Credit (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012 Rate	Dec. 31, 2011 Rate
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 37
Line of Credit, Current	1.7	21.4
Line of Credit Facility, Remaining Borrowing Capacity	35.6
Short-term Debt, Weighted Average Interest Rate	2.00%	2.00%
CTWS Line of Credit A [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	15
CTWS Line of Credit B [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	20
BSWC Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 2