Sale of California Water Service (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
California Water Service Group Stock [Abstract]
Available for Sale Marketable Security, Shares Sold		159,151
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds		$ 4,510
Fees Incurred on Sale of Available for Sale Securities		20
Available-for-sale Securities, Gross Realized Gain (Loss)		3,197	$ 0	$ 3,197	$ 0
Available for Sales Securities, Tax on Realized Gain	$ 1,303
Gain (Loss) on Sale of Securities, Net		1,894
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		$ 1,742	$ 0	$ 1,742	$ 0
Available for Sale Marketable Security, Shares Held		100,000		100,000