Share-Based Compensation Plans And Other Incentive Plans (Restricted Stock And Restricted Stock Unit Activity) (Details) (Restricted Stock And Restricted Stock Units, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014 employee	Dec. 31, 2013 employee	Dec. 31, 2012 employee
Restricted Stock And Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RS and RSU outstanding at January 1	3,728	6,299	8,990
Granted, RS and RSU	1,235	1,558	1,657
Vested, RS and RSU	(2,445)	(3,610)	(3,845)
Terminated, canceled or expired, RS and RSU	(765)	(519)	(503)
RS and RSU outstanding at December 31	1,753	3,728	6,299
Approx. number of employees granted RSUs	1,979	2,295	2,355
RS and RSU outstanding at January 1, Wtd Avg. Grant Date Fair Value	$ 49	$ 41	$ 40
Granted, Wtd Avg. Grant Date Fair Value	$ 63	$ 54	$ 49
Vested, Granted, Wtd Avg. Grant Date Fair Value	$ 48	$ 38	$ 41
Terminated, canceled or expired, Wtd Avg. Grant Date Fair Value	$ 54	$ 45	$ 33
RS and RSU outstanding at December 31, Wtd Avg. Grant Date Fair Value	$ 58	$ 49	$ 41

Share-Based Compensation Plans And Other Incentive Plans (Restricted Stock And Restricted Stock Unit Activity) (Details) (Restricted Stock And Restricted Stock Units, USD $)
In Thousands, except Per Share data, unless otherwise specified

12 Months Ended

Dec. 31, 2014

employee

Dec. 31, 2013

employee

Dec. 31, 2012

employee

Restricted Stock And Restricted Stock Units

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]

RS and RSU outstanding at January 1

3,728us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
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6,299us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

8,990us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Granted, RS and RSU

1,235us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

1,558us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

1,657us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Vested, RS and RSU

(2,445)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

(3,610)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

(3,845)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Terminated, canceled or expired, RS and RSU

(765)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

(519)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

(503)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

RS and RSU outstanding at December 31

1,753us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

3,728us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

6,299us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Approx. number of employees granted RSUs

1,979msi_NumberOfEmployeesGrantedRsus
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

2,295msi_NumberOfEmployeesGrantedRsus
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

2,355msi_NumberOfEmployeesGrantedRsus
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

RS and RSU outstanding at January 1, Wtd Avg. Grant Date Fair Value

$ 49us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 40us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Granted, Wtd Avg. Grant Date Fair Value

$ 63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 54us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 49us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Vested, Granted, Wtd Avg. Grant Date Fair Value

$ 48us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 38us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

Terminated, canceled or expired, Wtd Avg. Grant Date Fair Value

$ 54us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 45us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

$ 33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

RS and RSU outstanding at December 31, Wtd Avg. Grant Date Fair Value

$ 58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= msi_RestrictedStockAndRestrictedStockUnitsMember

- Definition

Number of Employees Granted RSUs

+ References

No definition available.

+ Details

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Namespace Prefix:	msi_
Data Type:	xbrli:integerItemType
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

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

-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=6415400&loc=d3e5070-113901

+ Details

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- Definition

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 as a result of the occurrence of a terminating event.

+ References

Reference 1: 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)(3)

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

+ Details

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- 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

Reference 1: 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

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- 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 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

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Balance Type:	na
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- 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 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

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- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) 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 or units.

+ References

Reference 1: 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

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- Definition

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

+ References

Reference 1: 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)(2)

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

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- 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

Reference 1: 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)(2)

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

+ Details

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