Debt (Long-term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Capital Lease Obligations	$ 10.2
Less: Unamortized discount	(9.2)	$ (6.3)
Total Long-term Debt	5,289.4	4,384.7
Less: Current portion of long-term debt	(371.3)	(435.6)
Long-term debt	4,918.1	3,949.1
Versum Financing [Member]
Debt Instrument [Line Items]
Senior Notes	$ 425.0
United States 5.0%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	5.00%
Debt Instruments Maturity Year	2018
Capital Lease Obligations	$ 0.5	0.7
Foreign 11.3%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	11.30%
Debt Instrument, Maturity Year Range, Start	2017
Debt Instrument, Maturity Year Range, End	2036
Capital Lease Obligations	$ 9.7	1.1
Debentures 8.75%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	8.75%
Debt Instruments Maturity Year	2021
Senior Notes	$ 18.4	18.4
Series D 7.3%
Debt Instrument [Line Items]
Weighted average interest rate	7.30%
Debt Instruments Maturity Year	2016
Medium-term Notes	$ 0.0	32.1
Series E 7.6%
Debt Instrument [Line Items]
Weighted average interest rate	7.60%
Debt Instruments Maturity Year	2026
Medium-term Notes	$ 17.2	17.2
Note 2.0%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	2.00%
Debt Instruments Maturity Year	2016
Senior Notes	$ 0.0	350.0
Note 1.2%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	1.20%
Debt Instruments Maturity Year	2018
Senior Notes	$ 400.0	400.0
Note 4.375%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	4.375%
Debt Instruments Maturity Year	2019
Senior Notes	$ 400.0	400.0
Note 3.0%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	3.00%
Debt Instruments Maturity Year	2022
Senior Notes	$ 400.0	400.0
Note 2.75%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	2.75%
Debt Instruments Maturity Year	2023
Senior Notes	$ 400.0	400.0
Note 3.35%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	3.35%
Debt Instruments Maturity Year	2024
Senior Notes	$ 400.0	400.0
Senior Note 5.5% \| Versum Financing [Member]
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	5.50%
Debt Instruments Maturity Year	2024
Senior Notes	$ 425.0	0.0
Term Loan B 3.346% \| Versum Financing [Member]
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	3.346%
Debt Instruments Maturity Year	2023
Term Loan	$ 575.0	0.0
Variable-rate industrial revenue bonds .68%
Debt Instrument [Line Items]
Weighted average interest rate	0.68%
Debt Instrument, Maturity Year Range, Start	2035
Debt Instrument, Maturity Year Range, End	2050
Other Long-term Debt	$ 769.9	769.9
Other 1.3%
Debt Instrument [Line Items]
Weighted average interest rate	1.30%
Debt Instrument, Maturity Year Range, Start	2018
Debt Instrument, Maturity Year Range, End	2019
Other Long-term Debt	$ 25.7	35.0
Eurobonds 4.625%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	4.625%
Debt Instruments Maturity Year	2017
Debt Payable In Other Currencies	$ 337.0	335.2
Eurobonds 2.0%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	2.00%
Debt Instruments Maturity Year	2020
Debt Payable In Other Currencies	$ 337.0	335.2
Eurobonds 1.0%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	1.00%
Debt Instruments Maturity Year	2025
Debt Payable In Other Currencies	$ 337.0	335.2
Eurobonds .375%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	0.375%
Debt Instruments Maturity Year	2021
Debt Payable In Other Currencies	$ 393.2	0.0
Other 4.4%
Debt Instrument [Line Items]
Interest rate of debt, stated percentage	4.40%
Debt Instrument, Maturity Year Range, Start	2016
Debt Instrument, Maturity Year Range, End	2022
Debt Payable In Other Currencies	$ 53.0	$ 161.0

Latest year the outstanding debt instruments are required to be repaid

No definition available.

Name:	apd_DebtInstrumentMaturityYearRangeEnd
Namespace Prefix:	apd_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Earliest year the outstanding debt instruments are required to be repaid

+ References

No definition available.

+ Details

Name:	apd_DebtInstrumentMaturityYearRangeStart
Namespace Prefix:	apd_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Year the outstanding debt instruments are required to be repaid

+ References

No definition available.

+ Details

Name:	apd_DebtInstrumentsMaturityYear
Namespace Prefix:	apd_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Payable In Other Currencies

+ References

No definition available.

+ Details

Name:	apd_DebtPayableInOtherCurrencies
Namespace Prefix:	apd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Term Loan

+ References

No definition available.

+ Details

Name:	apd_TermLoan
Namespace Prefix:	apd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 7

+ Details

Name:	us-gaap_CapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

Name:	us-gaap_LongTermDebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

Name:	us-gaap_LongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value at the balance sheet date of a financial instrument used to receive debt funding on a regular basis with original maturities ranging from 5-10 years.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

+ Details

Name:	us-gaap_MediumTermNotes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_OtherLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_SeniorNotes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=apd_VersumFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	apd_DebtGeographicRegionAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	apd_DebtGeographicRegionAxis=apd_ForeignMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_DebenturesEightPointSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_MediumTermNotesSevenPointThreePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_MediumTermNotesSevenPointSixPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNotesTwoPointZeroPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNoteOnePointTwoPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNotesFourPointThreeSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNoteThreePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNoteTwoPointSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNoteThreePointThreeFivePercentMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_SeniorNoteFivePointFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_TermLoanbThreePointThreeFourSixPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_VariableRateIndustrialRevenueBondsPointSixEightPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_OtherOnePointThreePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_EurobondsFourPointSixTwoFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_EurobondsTwoPointZeroPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_EurobondsOnePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_EurobondsPointThreeSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=apd_OtherFourPointFourPercentMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: