Preferred Stock Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2013	Jun. 30, 2015	Aug. 31, 2011
Class of Stock Disclosures [Abstract]
Company issued warrants			574,953
Exercise price of the warrants		$ 0.125	$ 0.09
Fair value of preferred stock warrant liability, probability of IPO scenario, percentage	20.00%
Fair value of preferred stock warrant liability, probability of merger scenario, percentage	10.00%
Fair value of preferred stock warrant liability, probability of stay private scenario, percentage	70.00%
Convertible preferred stock warrant liability	$ 6.5

Convertible preferred stock warrant liability.

No definition available.

Name:	ardx_ConvertiblePreferredStockWarrantLiability
Namespace Prefix:	ardx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of preferred stock warrant liability, probability of initial public offering scenario, percentage.

+ References

No definition available.

+ Details

Name:	ardx_FairValueOfPreferredStockWarrantLiabilityProbabilityOfInitialPublicOfferingScenarioPercentage
Namespace Prefix:	ardx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of preferred stock warrant liability, probability of merger scenario, percentage.

+ References

No definition available.

+ Details

Name:	ardx_FairValueOfPreferredStockWarrantLiabilityProbabilityOfMergerScenarioPercentage
Namespace Prefix:	ardx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of preferred stock warrant liability, probability of stay private scenario, percentage.

+ References

No definition available.

+ Details

Name:	ardx_FairValueOfPreferredStockWarrantLiabilityProbabilityOfStayPrivateScenarioPercentage
Namespace Prefix:	ardx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- 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

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares issued for each share of convertible preferred stock that is converted.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29
-Article 5

+ Details

Name:	us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant