Balancing and Memorandum Account Recovery Procedures (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 26, 2015	Jan. 05, 2015
Memorandum Accounts [Roll Forward]
Beginning Balance	$ (789)	$ (1,699)	$ (1,377)	$ (1,896)
Revenue Increase(Reduction)	397	187	821	384
Refunds (Collections)	163	0	327	0
Ending Balance	(229)	(1,512)	(229)	(1,512)
Balancing Accounts [Roll Forward]
Beginning Balance	46,358	8,978	48,438	9,585
Revenue Increase(Reduction)	400	1,332	1,543	725
Refunds (Collections)	(3,809)	0	(7,032)	0
Ending Balance	42,949	10,310	42,949	10,310
Balancing and Memorandum Account [Roll Forward]
Beginning Balance	45,569	7,279	47,061	7,689
Revenue Increase(Reduction)	797	1,519	2,364	1,109
Refunds (Collections)	(3,646)	0	(6,705)	0
Ending Balance	42,720	8,798	42,720	8,798
Authorized Regulatory Surcharge, Gross			1,937
Net under-collected balancing and memorandum accounts	9,122		9,122
Memorandum Account, Recovery Request					$ 9,567	$ 976
Water supply balancing accounts
Balancing Accounts [Roll Forward]
Beginning Balance	825	(2,772)	890	(2,378)
Revenue Increase(Reduction)	304	1,551	292	1,157
Refunds (Collections)	(59)	0	(112)	0
Ending Balance	1,070	(1,221)	1,070	(1,221)
Pension balancing account
Balancing Accounts [Roll Forward]
Beginning Balance	423	9,765	1,412	9,734
Revenue Increase(Reduction)	143	(92)	(463)	(61)
Refunds (Collections)	(427)	0	(810)	0
Ending Balance	139	9,673	139	9,673
Drought Surcharges [Member]
Balancing Accounts [Roll Forward]
Beginning Balance	0	0	0	0
Revenue Increase(Reduction)	0	0	0	0
Refunds (Collections)	(80)	0	(80)	0
Ending Balance	(80)	0	(80)	0
Balancing and memorandum accounts, net
Balancing Accounts [Roll Forward]
Beginning Balance	43,517	0	44,400	0
Revenue Increase(Reduction)	61	0	1,937	0
Refunds (Collections)	(3,211)	0	(5,970)	0
Ending Balance	40,367	0	40,367	0
Other, net
Balancing Accounts [Roll Forward]
Beginning Balance	1,593	1,985	1,736	2,229
Revenue Increase(Reduction)	(108)	(127)	(223)	(371)
Refunds (Collections)	(32)	0	(60)	0
Ending Balance	$ 1,453	$ 1,858	$ 1,453	$ 1,858