Equity and Noncontrolling Interests - Equity Attributable to Johnson Controls, Inc. and Noncontrolling Interests (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 11,311
Beginning balance	251
Beginning balance	11,562
Net income attributable to Johnson Controls, Inc.	507	469
Foreign currency translation adjustments	(351)	(14)
Realized and unrealized losses on derivatives	(10)	(1)
Realized and unrealized losses on marketable common stock	0	(2)
Pension and postretirement plans	(3)	(1)
Other comprehensive loss	(364)	(18)
Comprehensive income attributable to Johnson Controls, Inc.	143	451
Comprehensive income attributable to noncontrolling interests	39	33
Total comprehensive income	182	484
Ending balance	10,823	11,531
Ending balance	263	261
Ending balance	11,086	11,792
Equity Attributable to Johnson Controls, Inc
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	11,311	12,314
Net income attributable to Johnson Controls, Inc.	507	469
Foreign currency translation adjustments	(351)	(14)
Realized and unrealized losses on derivatives	(10)	(1)
Realized and unrealized losses on marketable common stock	0	(2)
Pension and postretirement plans	(3)	(1)
Other comprehensive loss	(364)	(18)
Comprehensive income attributable to Johnson Controls, Inc.	143	451
Cash dividends - common stock	(172)	(147)
Dividends attributable to noncontrolling interests	0	0
Repurchases of common stock	(600)	(1,199)
Other, including options exercised	141	112
Ending balance	10,823	11,531
Equity Attributable to Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	251	260
Income attributable to noncontrolling interests	20	22
Foreign currency translation adjustments	0	0
Realized and unrealized gains on derivatives	0	0
Realized and unrealized losses on marketable common stock	0	0
Pension and postretirement plans	0	0
Other comprehensive loss	0	0
Comprehensive income attributable to noncontrolling interests	20	22
Cash dividends - common stock	0	0
Dividends attributable to noncontrolling interests	(8)	(21)
Repurchases of common stock	0	0
Other, including options exercised	0	0
Ending balance	263	261
Total Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	11,562	12,574
Net income	527	491
Foreign currency translation adjustments	(351)	(14)
Realized and unrealized losses on derivatives	(10)	(1)
Realized and unrealized losses on marketable common stock	0	(2)
Pension and postretirement plans	(3)	(1)
Other comprehensive loss	(364)	(18)
Total comprehensive income	163	473
Cash dividends - common stock	(172)	(147)
Dividends attributable to noncontrolling interests	(8)	(21)
Repurchases of common stock	(600)	(1,199)
Other, including options exercised	141	112
Ending balance	$ 11,086	$ 11,792