Termination fee, payable by the Company to the Parent, if Merger Agreement is terminated under certain circumstances

No definition available.

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- Definition

Potential increase to existing liability for share-based arrangements, contingent on the completion of the merger agreement

+ References

No definition available.

+ Details

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Namespace Prefix:	arii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Termination fee, payable by the Parent to the Company, if Merger Agreement is terminated under certain circumstances

+ References

No definition available.

+ Details

Name:	arii_Reverseagreementterminationfeecontingent
Namespace Prefix:	arii_
Data Type:	xbrli:monetaryItemType
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- Definition

Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	dei_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

+ References

No definition available.

+ Details

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

- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

+ Details

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

- Definition

The cash inflow associated with the amount received by a corporation from a shareholder during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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Subsequent Events (Details) - USD ($)	3 Months Ended
Subsequent Events (Details) - USD ($)	Dec. 31, 2018	Dec. 27, 2018	Oct. 26, 2018	Oct. 22, 2018	Sep. 30, 2018
Subsequent Event [Line Items]
Deferred Compensation Share-based Arrangements, Contingent Liability					$ 5,200,000
Entity Common Stock, Shares Outstanding			19,083,878
Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent					$ 3,400,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash dividend declared (usd per share)		$ 0.40
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 70.00
Agreement termination fee, contingent				$ 65,000,000
Reverse agreement termination fee, contingent				130,000,000
Proceeds from Contributed Capital	$ 440,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted				$ 130,250,000