Aggregate Principal Amount of Senior Notes, Redemption Price, Percentage

No definition available.

Name:	nuan_AggregatePrincipalAmountOfSeniorNotesRedemptionPricePercentage
Namespace Prefix:	nuan_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Conversion Circumstance, Number of Consecutive Business Days

+ References

No definition available.

+ Details

Name:	nuan_DebtInstrumentConversionCircumstanceNumberOfConsecutiveBusinessDays
Namespace Prefix:	nuan_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Conversion Circumstance, Number of Consecutive Trading Days

+ References

No definition available.

+ Details

Name:	nuan_DebtInstrumentConversionCircumstanceNumberOfConsecutiveTradingDays
Namespace Prefix:	nuan_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Conversion Circumstance, Number of Trading Days

+ References

No definition available.

+ Details

Name:	nuan_DebtInstrumentConversionCircumstanceNumberOfTradingDays
Namespace Prefix:	nuan_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt issuance Percentage of Principal Amount

+ References

No definition available.

+ Details

Name:	nuan_DebtissuancePercentageofPrincipalAmount
Namespace Prefix:	nuan_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Principal Amount Per Note Used in Conversion Rate

+ References

No definition available.

+ Details

Name:	nuan_PrincipalAmountPerNoteUsedInConversionRate
Namespace Prefix:	nuan_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage

+ References

No definition available.

+ Details

Name:	nuan_RatioOfCommonStockClosingPriceToDebtConversionPricePercentage
Namespace Prefix:	nuan_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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

- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

+ Details

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

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031898-161870

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
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

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

+ 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

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28567-108399

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

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

- Definition

The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromConvertibleDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfConvertibleDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=nuan_EndingOnLastTradingDayOfPreviousFiscalQuarterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Credit Facilities and Debt 1.50% Convertible Debentures due 2035 (Details) - USD ($)	3 Months Ended			12 Months Ended
	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2014	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2012	Nov. 01, 2017	Jun. 30, 2017	Dec. 07, 2015	Jun. 01, 2015	Oct. 24, 2011
Debt Instrument [Line Items]
Long-term debt, face value	$ 2,137,000,000.0			$ 2,137,000,000.0	$ 2,437,000,000.0
Proceeds from long-term debt, net of issuance costs				0	0	$ 837,482,000
Debt Issuance Costs, Noncurrent, Net	511,000			511,000	$ 843,000
Convertible Debentures One Percent Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Long-term debt, face value										$ 676,500,000
Convertible debentures, interest rate					1.00%				1.00%
Proceeds from long-term debt, net of issuance costs					$ 663,800,000
Convertible Debt, Noncurrent										495,400,000
Debt Instrument, Convertible, Carrying Amount of Equity Component										$ 181,100,000
Debt Instrument, Unamortized Discount	$ 91,600,000			$ 91,600,000	$ 116,900,000
Debt Instrument, Convertible, Conversion Price										$ 27.22
Convertible Debentures One Point Five Percent Due November One Twenty Thirty Five [Member] [Member]
Debt Instrument [Line Items]
Long-term debt, face value											$ 263,900,000
Convertible debentures, interest rate	1.50%			1.50%	1.50%
Debt issuance Percentage of Principal Amount											97.09%
Debt Instrument, Unamortized Discount (Premium), Net											$ 7,700,000
Convertible Debt, Noncurrent											208,600,000
Debt Instrument, Convertible, Carrying Amount of Equity Component											$ 55,300,000
Debt Instrument, Unamortized Discount	$ 22,700,000			$ 22,700,000	$ 32,800,000
Debt Instrument, Convertible, Conversion Price											$ 23.26
Debt Instrument Conversion Circumstance Number Of Consecutive Business Days				5 days
Aggregate Principal Amount of Senior Notes, Redemption Price, Percentage				100.00%
2.75% Convertible Debentures due November 1, 2031
Debt Instrument [Line Items]
Long-term debt, face value								$ 46,600,000		$ 395,500,000		$ 690,000,000.0
Convertible debentures, interest rate	2.75%		2.75%	2.75%	2.75%							2.75%
Repayments of Convertible Debt	$ 256,200,000	$ 331,200,000	$ 38,300,000	$ 17,800,000	$ 38,300,000	$ 256,200,000
Proceeds from long-term debt, net of issuance costs					253,200,000
Proceeds from Convertible Debt							$ 676,100,000
Convertible Debt, Noncurrent												$ 533,600,000
Debt Instrument, Convertible, Carrying Amount of Equity Component												$ 156,400,000
Debt Instrument, Unamortized Discount	0			$ 0	$ 0
Debt Instrument, Convertible, Conversion Price												$ 32.30
Debt Instrument Conversion Circumstance Number Of Consecutive Business Days				5 days
Principal Amount Per Note Used In Conversion Rate	$ 1,000			$ 1,000
Aggregate Principal Amount of Senior Notes, Redemption Price, Percentage				100.00%
Minimum \| Convertible Debentures One Percent Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage										130.00%
Debt Instrument Conversion Circumstance Number Of Trading Days					20 days
Minimum \| Convertible Debentures One Point Five Percent Due November One Twenty Thirty Five [Member] [Member]
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage	130.00%			130.00%
Debt Instrument Conversion Circumstance Number Of Trading Days				20 days
Minimum \| 2.75% Convertible Debentures due November 1, 2031
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage	130.00%			130.00%
Debt Instrument Conversion Circumstance Number Of Trading Days				20 days
Maximum \| Convertible Debentures One Percent Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage										98.00%
Debt Instrument Conversion Circumstance Number Of Trading Days					30 days
Principal Amount Per Note Used In Conversion Rate										$ 1,000
Maximum \| Convertible Debentures One Point Five Percent Due November One Twenty Thirty Five [Member] [Member]
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage	98.00%			98.00%
Maximum \| 2.75% Convertible Debentures due November 1, 2031
Debt Instrument [Line Items]
Ratio of Common Stock Closing Price to Debt Conversion Price, Percentage	98.00%			98.00%
Ending on Last Trading Day of Previous Fiscal Quarter [Member] \| Convertible Debentures One Point Five Percent Due November One Twenty Thirty Five [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument Conversion Circumstance Number Of Consecutive Trading Days				30 days
Ending on Last Trading Day of Previous Fiscal Quarter [Member] \| 2.75% Convertible Debentures due November 1, 2031
Debt Instrument [Line Items]
Debt Instrument Conversion Circumstance Number Of Consecutive Trading Days				30 days