Name:	str_DateShareBasedAwardWillBeDistributed
Namespace Prefix:	str_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

End date of performance share performance period

No definition available.

Name:	str_EndDateOfPerformanceSharePerformancePeriod
Namespace Prefix:	str_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

The number of restricted stock units issued during the period.

No definition available.

Name:	str_NumberOfRestrictedStockUnitsIssued
Namespace Prefix:	str_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The number of years the target number of performance shares for each executive officer is subject to adjustment upward or downward based on the company's performance with respect to specified performance criteria relative to a specified peer group of companies.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOfAwardIsSubjectToAdjustment
Namespace Prefix:	str_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of shares reserved for issuance under stock option agreements awarded under the plan, to officers, employees and nonemployee directors of the equity method investee, that validly exist and are outstanding as of the balance-sheet date, including vested options.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAwardedToEquityMethodInvestee
Namespace Prefix:	str_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The number of outstanding awards on stock option plans for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Granted to certain officers, employees and non-employee directors of the Company as a result of the Spinoff and bifurcation of share-based awards.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedNumberRelatedToSpinoffAndBifurcationOfAwards
Namespace Prefix:	str_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are nonvested. Granted to certain officers, employees and non-employee directors of the Company as a result of the Spinoff and bifurcation of share-based awards.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedWeightedAverageExercisePriceRelatedToSpinoffAndBifurcationOfAwards
Namespace Prefix:	str_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	instant

The number of unvested restricted shares awarded under the plan, to officers, employees and nonemployee directors of the equity method investee, that validly exist and are outstanding as of the balance-sheet date.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedSharesAwardedToEquityMethodInvestee
Namespace Prefix:	str_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The number of outstanding unvested restricted shares for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Granted to certain officers, employees and non-employee directors of the Company as a result of the Spinoff and bifurcation of share-based awards.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedSharesRelatedToSpinoffAndBifurcationOfAwards
Namespace Prefix:	str_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The weighted average fair value of unvested restricted shares for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares, awarded to officers, employees and nonemployee directors of the equity method investee.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedSharesWeightedAverageGrantDateFairValue
Namespace Prefix:	str_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	instant

The weighted average fair value of unvested restricted shares for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Granted to certain officers, employees and non-employee directors of the Company as a result of the Spinoff and bifurcation of share-based awards.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedSharesWeightedAverageGrantDateFairValueRelatedToSpinoffAndBifurcationOfAwards
Namespace Prefix:	str_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	instant

The weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. These grantees are certain officers, employees and nonemployee directors of the equity method investee.

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageExercisePriceOptionsAwardedToEquityMethodInvestee
Namespace Prefix:	str_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	instant

The weighted-average period remaining as of the balance-sheet date until option expiration pertaining to the outstanding stock options awarded to certain officers, employees and nonemployee directors of the equity method investee, which may be expressed in a variety of ways (for example, years, months).

No definition available.

Name:	str_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageRemainingLifeOptionsAwardedToEquityMethodInvestee
Namespace Prefix:	str_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

The weighted average fair value at grant for nonvested restricted stock units issued during the period.

No definition available.

Name:	str_WeightedAveragePriceOfRestrictedStockUnitsIssued
Namespace Prefix:	str_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	duration

Description of the period of time over which an employee's right to exercise a restricted stock unit award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, which may be expressed in a variety of ways (for example, in years, month and year).

No definition available.

Name:	str_WeightedAverageVestingPeriodOfRestrictedStockUnitsIssued
Namespace Prefix:	str_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

As of the balance-sheet date, the aggregate unrecognized cost of share-based awards made to employees under share-based compensation plans that have yet to vest.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph h

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The weighted average period over which unrecognized compensation is expected to be recognized for share-based compensation plans, using a decimal to express in number of years.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph h

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Details

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

Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph a

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

Share-based compensation cost during the period with respect to the award, which will be recognized in income (as well as the total recognized tax benefit) or capitalized as part of the cost of an asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(1)

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64, 65

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

The number of shares issuable under a share-based award plan pertaining to grants made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

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

The weighted average fair value as of grant dates pertaining to a share-based award plan other than a stock option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(d)