Investments and Fair Value of Financial Instruments - Additional Information (Detail)	9 Months Ended
Sep. 30, 2017 USD ($) Investment	Dec. 31, 2016 USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investment in continuous unrealized loss position for more than twelve months	$ 0
Maturity of short-term investments	2017
Number of long term investments mature in next year \| Investment	2
Amortized Cost	$ 15,402,000	$ 52,613,000
Maturity of long term investments	2018
Short-term Investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	$ 3,900,000

Maturity of long term investments.

No definition available.

Name:	rkda_MaturityOfLongTermInvestments
Namespace Prefix:	rkda_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Maturity of short term investments.

+ References

No definition available.

+ Details

Name:	rkda_MaturityOfShortTermInvestments
Namespace Prefix:	rkda_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of long term investments mature in next year.

+ References

No definition available.

+ Details

Name:	rkda_NumberOfLongTermInvestmentsMatureInNextYear
Namespace Prefix:	rkda_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: