Consolidated Statements Of Cash Flow (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Consolidated Statements Of Cash Flow [Abstract]
Debt component of allowance for funds used during construction	$ 721	$ 580

Debt component of allowance for funds used during construction

No definition available.

Name:	wtr_DebtComponentOfAllowanceForFundsUsedDuringConstruction
Namespace Prefix:	wtr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration