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Number of acquisitions which increased Company's ownership from noncontrolling to controlling interest

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Number of businesses divested.

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Number Of Joint Ventures Divested

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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In a business combination achieved in stages, this element represents the amount of gain recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

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Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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The gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. It is included in income from continuing operations before income taxes in the income statement.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The net cash inflow or outflow associated with the aggregate amount of adjustment to the purchase price of a previous acquisition.

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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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Acquisitions and Divestitures - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015
Acquisitions And Discontinued Operations [Line Items]
Cash paid for business acquisition	$ 9	$ 0	$ 22		$ 128
Goodwill recorded in connection with business acquisitions			30us-gaap_GoodwillAcquiredDuringPeriod	877us-gaap_GoodwillAcquiredDuringPeriod
Sales price of divestiture	141	0	141		13
Reduction in goodwill related to business divestitures			9	265
Aggregate non-cash gain recorded due to acquisition	0	0	0		19
Individually Immaterial Acquisitions
Acquisitions And Discontinued Operations [Line Items]
Number of acquisitions			3		2
Purchase price, net of cash acquired			47
Cash paid for business acquisition			18		128
Goodwill recorded in connection with business acquisitions			9		100
Goodwill adjustment related to previous acquisition					2
Number of acquisitions which increased Company's ownership from noncontrolling to controlling interest					1
Aggregate non-cash gain recorded due to acquisition					19
Air Distribution Technologies, Inc. [Member]
Acquisitions And Discontinued Operations [Line Items]
Goodwill recorded in connection with business acquisitions				837
Adjustment to purchase price of previous acquisition			4
Goodwill adjustment related to previous acquisition			21
Brookfield Johnson Controls
Acquisitions And Discontinued Operations [Line Items]
Number Of Joint Ventures Divested	2		2
Proceeds from Divestiture of Interest in Joint Venture	141
Discontinued operation, gain (loss) on divestiture	200		200
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	127
Reduction in goodwill related to business divestitures	20
Disposal group, individually immaterial
Acquisitions And Discontinued Operations [Line Items]
Sales price of divestiture					13
Gain on Disposal					9
Reduction in goodwill related to business divestitures					0
Number of divestitures					1
Expected proceeds \| Global Workplace Solutions
Acquisitions And Discontinued Operations [Line Items]
Sales price of divestiture						1,475
Building Efficiency Other
Acquisitions And Discontinued Operations [Line Items]
Goodwill recorded in connection with business acquisitions			21	837
Reduction in goodwill related to business divestitures			$ 0	$ 0