Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013 Customer	Jun. 30, 2013 Customer
Schedule Of Significant Accounting Policies [Line Items]
Restricted cash	$ 7.2	$ 7.2
Customer prepayments	5.7	5.7
Customer prepayments, current	2.4	2.4
Net product sales
Schedule Of Significant Accounting Policies [Line Items]
Number of customers accounted for net product sales	3	4
Net product sales \| Customer One Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	26.00%	24.00%
Net product sales \| Customer Two Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	15.00%	17.00%
Net product sales \| Customer Three Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage	15.00%	14.00%
Net product sales \| Customer Four Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		10.00%
Accounts receivable
Schedule Of Significant Accounting Policies [Line Items]
Number Of customers accounted for accounts receivable		5
Accounts receivable \| Customer One Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		29.00%
Accounts receivable \| Customer Two Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		17.00%
Accounts receivable \| Customer Three Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		14.00%
Accounts receivable \| Customer Four Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		14.00%
Accounts receivable \| Customer Five Product Sales
Schedule Of Significant Accounting Policies [Line Items]
Customers concentration risk, percentage		12.00%
Letter of Credit
Schedule Of Significant Accounting Policies [Line Items]
Restricted cash	$ 5.8	$ 5.8

The current portion of prepayments received from customers for goods or services.

No definition available.

Name:	aria_CustomerPrepayments
Namespace Prefix:	aria_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The current portion of prepayments received from customers for goods or services during the current quarter.

+ References

No definition available.

+ Details

Name:	aria_CustomerPrepaymentsCurrent
Namespace Prefix:	aria_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of individual customers accounting for more than ten percent of accounts receivable.

+ References

No definition available.

+ Details

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Namespace Prefix:	aria_
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Balance Type:	na
Period Type:	duration

- Definition

Number of individual customers accounting for more than ten percent of net product sales.

+ References

No definition available.

+ Details

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Namespace Prefix:	aria_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13531-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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 210.5-02.1)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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