Fixed Charge Coverage Ratio Required by Debt Covenant

No definition available.

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- Definition

Expansion feature included in the line of credit agreement, allowing the Company to increase its maximum borrowing capacity under the agreement at a later date.

+ References

No definition available.

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- Definition

Net Leverage Ratio Required by Debt Covenant

+ References

No definition available.

+ Details

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- Definition

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-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

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- Definition

Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=84164758&loc=d3e45014-112735

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- 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
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-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Balance Type:	credit
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

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Weighted average interest rate of short-term debt outstanding calculated over time.

+ References

No definition available.

+ Details

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- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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- Details

Name:	us-gaap_CreditFacilityAxis=omn_EurodollarRevolverDomain
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- Details

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Debt and Credit Lines Additional Information (Details) € in Millions	3 Months Ended			6 Months Ended
	May 31, 2019 USD ($)	May 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	May 31, 2019 USD ($)	May 31, 2018 USD ($)	May 31, 2019 EUR (€)	Nov. 30, 2018 USD ($)
Debt Instrument [Line Items]
Short-term Debt, Weighted Average Interest Rate, over Time				5.74%	5.04%
Capital Leased Assets	$ 14,300,000			$ 14,300,000
Amortization of Debt Issuance Costs and Discounts	300,000	$ 300,000		700,000	$ 600,000
Debt issuance costs write-off	$ 0	$ 0	$ 800,000	$ 0	$ 800,000
Senior Secured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Expiration Date				Aug. 26, 2021
Line of Credit Facility, Maximum Amount Outstanding During Period				$ 25,000,000.0
Line of Credit Facility, Covenant Terms	1.1			1.1		1.1
Long-term Line of Credit, Outstanding Borrowings	$ 13,000,000.0			$ 13,000,000.0
Line of Credit Facility, Remaining Borrowing Capacity	53,100,000			53,100,000
Eurodollar Revolver [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Expansion Feature \| €						€ 9.0
Long-term Line of Credit, Outstanding Borrowings \| €						1.5
Line of Credit Facility, Remaining Borrowing Capacity \| €						9.3
Line of Credit Facility, Maximum Borrowing Capacity \| €						€ 16.0
Foreign line of credit
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	11,800,000			11,800,000			$ 7,000,000.0
Term Loan B [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 350,000,000.0			$ 350,000,000.0
Net Leverage Ratio Required by Debt Covenant	5.0			5.0		5.0
Debt Instrument, Basis Spread on Variable Rate				3.25%
Line of Credit Facility, Expansion Feature	$ 120,000,000.0			$ 120,000,000.0
Repayments of Debt			$ 40,000,000.0