INCOME TAXES (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Developer deposits for extension agreements and contributions in aid of construction	$ 45,670	$ 44,775
Net operating loss carryforward and tax credits	15,042	19,866
Other	11,263	8,904
Total deferred tax assets	71,975	73,545
Deferred tax liabilities:
Property related basis and depreciation differences	309,088	272,958
WRAM/MCBA and interim rates balancing accounts	23,894	30,871
Other	3,890	4,308
Total deferred tax liabilities	336,872	308,137
Total deferred tax liabilities	264,897	234,592
Noncurrent portion of deferred income tax	264,897	214,842
Reconciliation of the changes in unrecognized tax benefits
Balance at beginning of year	7,916	612	$ 0
Additions for tax positions taken during prior year	0	0	0
Additions for tax positions taken during current year	2,382	7,304	612
Reductions for tax positions taken during a prior year	0	0	0
Lapse of statute of limitations	0	0	0
Balance at end of year	$ 10,298	$ 7,916	$ 612