Restricted Stock Units Activity (Details) (Restricted Stock Units (RSUs) [Member], USD $)	9 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	745,276	777,666
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested But Deferred Number	20,066	45,189
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Number	765,342	822,855
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Outstanding Weighted Average Grant Date Fair Value	$ 50.23	$ 47.14
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	271,821
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Grants In Period	271,821
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 57.14
Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Unvested	1,988
Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Vested But Deferred	52
Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Total Number	2,040
Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents, Weighted Average Grant Date Fair Value	$ 48.06
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(236,328)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Vested In Period	(236,328)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 48.64
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred Unvested	(1,691)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred	1,691
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred Total	0
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested But Deferred Issued In Period	(26,866)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Issued In Period	(26,866)
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Issued in Period Weighted Average Grant Date Fair Value	$ 46.69
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(68,180)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Forfeited In Period	(68,180)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value	$ 47.61

Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Issued in Period Weighted Average Grant Date Fair Value

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIssuedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	morn
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Grant Date Fair Value

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageGrantDateFairValue
Namespace Prefix:	morn
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Total, Forfeited In Period

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalForfeitedInPeriod
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Total, Grants In Period

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalGrantsInPeriod
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Total, Issued In Period

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalIssuedInPeriod
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Total, Number

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalNumber
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Vested In Period

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalVestedInPeriod
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedButDeferred
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Vested But Deferred, Issued In Period

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedButDeferredIssuedInPeriod
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Vested But Deferred, Number

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedButDeferredNumber
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred Total

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedButDeferredTotal
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred Unvested

+ Details

Name:	morn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedButDeferredUnvested
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Total Number

+ Details

Name:	morn_ShareBasedCompensationArrangementsByShareBasedAwardEquityInstrumentsOtherThanOptionsDividendEquivalentsTotalNumber
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Unvested

+ Details

Name:	morn_ShareBasedCompensationArrangementsByShareBasedAwardEquityInstrumentsOtherThanOptionsDividendEquivalentsUnvested
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents Vested But Deferred

+ Details

Name:	morn_ShareBasedCompensationArrangementsByShareBasedAwardEquityInstrumentsOtherThanOptionsDividendEquivalentsVestedButDeferred
Namespace Prefix:	morn
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangements By Share-based Award Equity Instruments Other than Options Dividend Equivalents, Weighted Average Grant Date Fair Value

+ Details

Name:	morn_ShareBasedCompensationArrangementsByShareBasedAwardEquityInstrumentsOtherThanOptionsDividendEquivalentsWeightedAverageGrantDateFairValue
Namespace Prefix:	morn
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

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

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap
Data Type:	num:perShareItemType
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.

+ Details

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