Regulatory Decision and Related Accounting and Policy Changes - Summary of Collective Revenue Requirement Phased-in Over Time (Details)	Sep. 30, 2020 USD ($)
Incremental
2015	$ 1,083
2016	887
2017	335
2018	335
2019	335
2020	335
2021	335
Cumulative
2015	1,083
2016	1,970
2017	2,305
2018	2,640
2019	2,975
2020	3,310
2021	$ 3,645

Cumulative revenue requirement increase in seventh year.

No definition available.

Name:	gwrs_CumulativeRevenueRequirementIncreaseInSeventhYear
Namespace Prefix:	gwrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant