Net Shares Outstanding After Cashless Exercise

No definition available.

Name:	gwrs_NetSharesOutstandingAfterCashlessExercise
Namespace Prefix:	gwrs_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price, Number of Days Prior to Grant Date Used to Determine Exercise Price

+ References

No definition available.

+ Details

Name:	gwrs_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsExercisePriceNumberofDaysPriortoGrantDateUsedtoDetermineExercisePrice
Namespace Prefix:	gwrs_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares options (or share units) previously exercised.

+ References

No definition available.

+ Details

Name:	gwrs_SharesExercised
Namespace Prefix:	gwrs_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Stock Compensation Shares Exercised Utilizing Cashless Exercise

+ References

No definition available.

+ Details

Name:	gwrs_StockCompensationSharesExercisedUtilizingCashlessExercise
Namespace Prefix:	gwrs_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of noncash expense for share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

+ Details

Name:	us-gaap_ShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of noncash expense for option under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

+ Details

Name:	us-gaap_StockOptionPlanExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PhantomShareUnitsPSUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_StockAppreciationRightsSARSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=gwrs_PhantomShareUnitsAndStockAppreciationRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gwrs_TwentySixteenStockOptionGrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gwrs_TwentySeventeenStockOptionGrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=gwrs_VestOnAugust2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=gwrs_VestOnAugust2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=gwrs_VestOnAugust2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gwrs_TwentyNineteenStockOptionGrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=gwrs_VestOnAugust2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=gwrs_VestOnAugust2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Deferred Compensation Awards - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					1 Months Ended		12 Months Ended
	Aug. 13, 2019	May 20, 2016	Nov. 14, 2013	Jul. 01, 2013	Aug. 31, 2017	May 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, options granted (in shares)							250,000
Options, exercise price per share (usd per share)							$ 10.12	$ 9.02	$ 8.69
Options forfeited							49,000	62,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number							633,000	498,000	740,000
Phantom Stock Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							36 months
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average days used to determine exercise price			30 days	5 days
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
PSUs and SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 1,400	$ 1,200
2016 stock option grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, options granted (in shares)						325,000
Options, exercise price per share (usd per share)		$ 7.50
Expiration period							3 years
Fair value of the stock option expense							$ 300
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							2 years
2016 stock option grant \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 0	100
Shares Exercised							325,000
Stock Compensation Shares Exercised Utilizing Cashless Exercise										125,000
Net Shares Outstanding After Cashless Exercise										27,364
Treasury Stock, Shares, Acquired							97,636
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number										0
2016 stock option grant \| Vest on May 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							2 years
2016 stock option grant \| Vest on May 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							50.00%
2017 stock option grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, options granted (in shares)					465,000
Expiration period							10 years
Fair value of the stock option expense							$ 1,100
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Split-adjusted exercise price of options (usd per share)					$ 9.40
2017 stock option grant \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 300
Shares Exercised							10,154
Options forfeited							67,950
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number							386,896
2017 stock option grant \| Vest on August 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
2017 stock option grant \| Vest on August 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
2017 stock option grant \| Vest on August 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
2017 stock option grant \| Vest on August 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
Twenty Nineteen Stock Option Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, options granted (in shares)	250,000
Expiration period							10 years
Fair value of the stock option expense							$ 800
Split-adjusted exercise price of options (usd per share)	$ 11.26
Twenty Nineteen Stock Option Grant [Member] \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 100	$ 0
Options forfeited							4,396
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number							245,604
Twenty Nineteen Stock Option Grant [Member] \| Vest on August 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Twenty Nineteen Stock Option Grant [Member] \| Vest on August 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
Twenty Nineteen Stock Option Grant [Member] \| Vest on August 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
Twenty Nineteen Stock Option Grant [Member] \| Vest On August 2022 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%
Twenty Nineteen Stock Option Grant [Member] \| Vest On August 2023 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage							25.00%