CONSOLIDATED STATEMENTS OF CHANGE IN COMMON SHAREHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	GOLDEN STATE WATER COMPANY	GOLDEN STATE WATER COMPANY Common Stock [Member]	GOLDEN STATE WATER COMPANY Retained Earnings [Member]
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		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
Balance (in shares) at Dec. 31, 2019		36,847,000			165
Beginning balances at Dec. 31, 2019	601,530	$ 255,566	345,964	551,188	$ 293,754	257,434
Add:
Net income	$ 14,072			11,202
Exercise of stock options and other issuance of Common Shares (in shares)	37,157	37,000
Exercise of stock options and other issuances of Common Shares	$ 30	$ 30
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements (Note 4)	193	193		254	254
Dividend equivalent rights on stock-based awards not paid in cash	52	52		46	46
Deduct:
Dividends on Common Shares	11,242		11,242	11,250		11,250
Dividend equivalent rights on stock-based awards not paid in cash	52		52	46		46
Ending balances at Mar. 31, 2020	$ 604,583	$ 255,841	$ 348,742	$ 551,394	$ 294,054	$ 257,340
Balances (in shares) at Mar. 31, 2020		36,884,000			165