Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Actual Allocation of Plan Assets [Table Text Block]

The Committee approves the target asset allocations.  Registrant’s pension and post-retirement plan weighted-average asset allocations at December 31, 2016 and 2015, by asset category are as follows:

	Pension Benefits				Post-Retirement Medical Benefits
Asset Category	2016		2015		2016		2015
Actual Asset Allocations:
Equity securities	57	%	55	%	58	%	60	%
Debt securities	38	%	40	%	39	%	38	%
Real Estate Funds	5	%	5	%	—	%	—	%
Cash equivalents	—	%	—	%	3	%	2	%
Total	100	%	100	%	100	%	100	%

Schedule of share-based compensation expenses

The following table presents share-based compensation expenses for the years ended December 31, 2016, 2015 and 2014.  These expenses resulting from restricted stock units, including performance awards, are included in administrative and general expenses in AWR's and GSWC’s statements of income:

	AWR						GSWC
	For The Years Ended December 31,						For The Years Ended December 31,
(in thousands)	2016		2015		2014		2016		2015		2014
Stock-based compensation related to:
Restricted stock units	$	2,538	$	2,754	$	2,222	$	2,118	$	2,443	$	1,748
Total stock-based compensation expense	$	2,538	$	2,754	$	2,222	$	2,118	$	2,443	$	1,748

Schedule of assumptions used to estimate fair value of each option grant on the grant date using the Black-Scholes option-pricing model

will be earned based on Registrant’s TSR compared to the TSR for a specific peer group of investor-owned water companies.

A summary of the status of Registrant’s outstanding performance awards to officers as of December 31, 2016, and changes during the year ended December 31, 2016, is presented below:

	Number of Performance awards		Weighted Average Grant-Date Value
Performance awards at January 1, 2016	131,953		$	30.66
Granted	29,758		40.81
Performance criteria adjustment	(8,100	)	28.09
Vested	(51,408	)	27.82
Performance awards at December 31, 2016	102,203		$	35.25

Summary of stock option activity

A summary of stock option activity as of December 31, 2016 and changes during the year ended December 31, 2016, are presented below:

	Number of Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Options outstanding at January 1, 2016	150,606		$	17.39
Granted	—		—
Exercised	(12,546	)	18.75
Forfeited or expired	(1,500	)	16.87
Options outstanding at December 31, 2016	136,560		$	17.27	1.92	$	3,863,731
Options exercisable at December 31, 2016	136,560		$	17.27	1.92	$	3,863,731

Summary of the status of Registrant's outstanding restricted stock units to employees and directors

A summary of the status of Registrant’s outstanding RSUs, excluding performance awards, to employees and directors as of December 31, 2016, and changes during the year ended December 31, 2016, is presented below:

	Number of Restricted Share Units		Weighted Average Grant-Date Value
Restricted share units at January 1, 2016	111,335		$	26.21
Granted	37,807		40.52
Vested	(40,555	)	27.03
Forfeited	(858	)	38.06
Restricted share units at December 31, 2016	107,729		$	30.83