INCOME TAXES (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Deferred tax assets:
Developer deposits for extension agreements and contributions in aid of construction	$ 45,587	$ 46,421
Other	4,464	4,378
Total deferred tax assets	50,051	50,799
Deferred tax liabilities:
Utility plant, principally due to depreciation differences	155,916	143,165
WRAM/MCBA balancing accounts	17,393	13,463
Other	3,645	5,977
Total deferred tax liabilities	176,954	162,605
Net deferred tax liabilities	126,903	111,806
Current portion of deferred income tax	10,535	4,722
Reconciliation of the changes in unrecognized tax benefits (at gross)
Balance at beginning of year	2,040	2,040
Balance at end of year	2,040	2,040
Total amount of penalties and interest accrued	$ 114	$ 114