Represents the amount of incremental capacity available so long as the entity meets certain conditions.

No definition available.

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

- Definition

Represents percentage of present value of the future cash flows remaining under the Existing Senior Credit Facilities.

+ References

No definition available.

+ Details

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Namespace Prefix:	alks_
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- Definition

Represents the amount of the required periodic payments applied to principal as percentage of original principal amount.

+ References

No definition available.

+ Details

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

- Definition

Represents the term of the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	alks_
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- Definition

Represents the term of the debt instrument before amendment.

+ References

No definition available.

+ Details

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Namespace Prefix:	alks_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The floor for the variable rate base of the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of repricing premium on the outstanding credit agreement balance if the prepayment is made in connection with an amendment to the agreement resulting in a refinancing transaction.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Represents the percentage of repricing premium on credit agreement being repaid if the prepayment is made in connection with a refinancing transaction.

+ References

No definition available.

+ Details

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

- Definition

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

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Balance Type:	credit
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- Details

Name:	us-gaap_DebtInstrumentLineItems
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- Definition

Amount of the required periodic payments applied to principal.

+ 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 210.5-02.22)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

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-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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

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

+ Details

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ 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 210.5-02.19,20)

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

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Article 5

+ Details

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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- 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

No definition available.

+ Details

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LONG-TERM DEBT (Details) (USD $)			12 Months Ended	1 Months Ended	0 Months Ended		0 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended			1 Months Ended
LONG-TERM DEBT (Details) (USD $)	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 2013 Term Loans	Sep. 30, 2012 2013 Term Loans LIBOR	Dec. 31, 2012 New Term Loan Facility	Mar. 31, 2013 New Term Loan Facility	Dec. 31, 2012 Term Loan B-1, due September 25, 2019	Feb. 29, 2012 Term Loan B-1, due September 25, 2019	Mar. 31, 2013 Term Loan B-1, due September 25, 2019	Feb. 28, 2013 Term Loan B-1, due September 25, 2019 LIBOR	Dec. 31, 2012 Term Loan B-2, due September 25, 2016	Feb. 29, 2012 Term Loan B-2, due September 25, 2016	Mar. 31, 2013 Term Loan B-2, due September 25, 2016	Feb. 28, 2013 Term Loan B-2, due September 25, 2016 LIBOR	Sep. 30, 2012 First Lien Term Loan, due September 16, 2017	Mar. 31, 2012 First Lien Term Loan, due September 16, 2017	Sep. 30, 2012 Second Lien Term Loan, due September 16, 2018	Mar. 31, 2012 Second Lien Term Loan, due September 16, 2018
Long-term debt
Total	$ 369,008,000	$ 444,460,000	$ 371,625,000						$ 296,029,000				$ 72,979,000			$ 306,822,000		$ 137,638,000
Less: current portion	(6,750,000)	(3,100,000)
Long-term debt	362,258,000	441,360,000
Aggregate principal amount									300,000,000				75,000,000		375,000,000
Repayment of term loan																	75,000,000
Interest rate, variable interest rate floor				1.00%						0.75%				0.00%
Variable interest rate base								LIBOR				LIBOR
Interest rate added to base rate (as a percent)										2.75%				2.75%
Term of loan before amendment			1 year
Term of loan			6 months
Percentage of repricing premium on outstanding credit agreement balance, if prepayment is made in connection with an amendment to the agreement resulting in a refinancing transaction			1.00%
Original issue discount	2,600,000								3,000,000				400,000
Term Loan quarterly amortization price as percentage of original principal amount									0.25%				1.25%
Required quarterly principal payments							800,000				900,000
Percentage of repricing premium on credit agreement being repaid if the prepayment is made in connection with a refinancing transaction					1.00%
Incremental capacity						$ 140,000,000
Percentage of present value of future cash flows remaining under Existing Senior Credit Facilities					10.00%