Reorganization Of Businesses (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012 employee	Dec. 31, 2011
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	$ 73,000,000	$ 86,000,000	$ 33,000,000
Net adjustment of accruals	(4,000,000)	(16,000,000)	(8,000,000)
Restructuring reserve	57,000,000us-gaap_RestructuringReserve	109,000,000us-gaap_RestructuringReserve	35,000,000us-gaap_RestructuringReserve	44,000,000us-gaap_RestructuringReserve
Additional charges	100,000,000us-gaap_RestructuringCharges	149,000,000us-gaap_RestructuringCharges	54,000,000us-gaap_RestructuringCharges
Cash Payments made towards exit costs	148,000,000us-gaap_PaymentsForRestructuring	59,000,000us-gaap_PaymentsForRestructuring	55,000,000us-gaap_PaymentsForRestructuring
Number of Employees Impacted By Reorganization of Business
Restructuring charges in the period for total employee severance (in number of employees)			1,000msi_RestructuringChargesEmployees
Restructuring charges in the period for direct employees' severance (in number of employees)			300
Restructuring charges in the period for indirect employees' severance (in number of employees)			700
Exit Costs
Restructuring Cost and Reserve [Line Items]
Net adjustment of accruals	0	0	1,000,000
Restructuring reserve	0	6,000,000	4,000,000	14,000,000
Additional charges	7,000,000	3,000,000	0
Cash Payments made towards exit costs	13,000,000	1,000,000	11,000,000
Employee Separation Costs
Restructuring Cost and Reserve [Line Items]
Net adjustment of accruals	(4,000,000)	(16,000,000)	(9,000,000)
Restructuring reserve	57,000,000	103,000,000	31,000,000	30,000,000
Additional charges	93,000,000	146,000,000	54,000,000
Cash Payments made towards exit costs	135,000,000	58,000,000	44,000,000
Number of Employees Impacted By Reorganization of Business
Restructuring charges in the period for total employee severance (in number of employees)	1,200	2,200
Restructuring charges in the period for direct employees' severance (in number of employees)	300	800
Restructuring charges in the period for indirect employees' severance (in number of employees)	900	1,400
Number of employees expected to be paid (in number of employees)	500		400	700
Continuing Operations
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	73,000,000	86,000,000	33,000,000
Net adjustment of accruals	(1,000,000)	(10,000,000)	(7,000,000)
Continuing Operations \| Cost of sales
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	9,000,000	16,000,000	6,000,000
Continuing Operations \| Other Charges
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	64,000,000	70,000,000	27,000,000
Continuing Operations \| Exit Costs
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	7,000,000	2,000,000
Continuing Operations \| Employee Separation Costs
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	67,000,000	94,000,000	35,000,000
Continuing Operations \| Building Impairment
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges			5,000,000
Discontinued Operations \| Employee Separation Costs
Restructuring Cost and Reserve [Line Items]
Cash Payments made towards exit costs	$ 50,000,000	$ 20,000,000	$ 20,000,000

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Restructuring charges in the period for direct employees' severance (in number of employees)

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Restructuring Charges Employees

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Restructuring Charges Employees Indirect

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Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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Amount of any reversal and other adjustment made during the period to the amount of a previously accrued liability for a specified type of restructuring cost, excluding adjustments for costs incurred during the period, costs settled during the period, and foreign currency translation adjustments.

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The aggregate amount provided for estimated restructuring charges, remediation costs, and asset impairment loss during an accounting period. Generally, these items are either unusual or infrequent, but not both (in which case they would be extraordinary items).

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