CONSOLIDATED STATEMENTS OF CHANGE IN COMMON SHAREHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Golden State Water Company [Member]	Golden State Water Company [Member] Common Stock [Member]	Golden State Water Company [Member] Retained Earnings [Member]
Balance (in shares) at Dec. 31, 2017		36,681,000			146
Beginning balances at Dec. 31, 2017	$ 529,945	$ 250,124	$ 279,821	$ 474,374	$ 242,181	$ 232,193
Add:
Net income	$ 10,782		10,782	8,890		8,890
Exercise of stock options and other issuance of Common Shares (in shares)	52,622	52,000
Exercise of stock options and other issuances of Common Shares	$ 340	$ 340
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements (Note 4)	(181)	(181)		(266)	(266)
Dividend equivalent rights on stock-based awards not paid in cash	56	56		49	49
Deduct:
Dividends on Common Shares	9,362		9,362	9,380		9,380
Dividend equivalent rights on stock-based awards not paid in cash	56		56	49		49
Ending balances at Mar. 31, 2018	531,524	$ 250,339	281,185	473,618	$ 241,964	231,654
Balances (in shares) at Mar. 31, 2018		36,733,000			146
Balance (in shares) at Dec. 31, 2018		36,758,000			165
Beginning balances at Dec. 31, 2018	558,223	$ 253,689	304,534	503,575	$ 292,412	211,163
Add:
Net income	$ 12,852			9,022		9,022
Exercise of stock options and other issuance of Common Shares (in shares)	37,376	37,000
Exercise of stock options and other issuances of Common Shares	$ 75	$ 75
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements (Note 4)	463	463		572	572
Dividend equivalent rights on stock-based awards not paid in cash	70	70		60	60
Deduct:
Dividends on Common Shares	10,113		10,113	10,100		10,100
Dividend equivalent rights on stock-based awards not paid in cash	70		70	60		60
Ending balances at Mar. 31, 2019	$ 561,500	$ 254,297	$ 307,203	$ 503,069	$ 293,044	$ 210,025
Balances (in shares) at Mar. 31, 2019		36,795,000			165