XML 18 R57.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2

Investments - Schedule of Proceeds From Sales and Maturities of Marketable Securities Plus Resulting Realized Gains and Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments Debt And Equity Securities [Abstract]
Proceeds from the sales and maturities of marketable securities	$ 224,602	$ 444,456	$ 464,494
Realized gains	997	4	9
Realized losses	$ 497	$ 268	$ 3

X

- Definition

Represents the profit realized on the sale of debt or equity securities categorized as held-to-maturity, trading securities and available-for-sale.

+ References

No definition available.

+ Details

Name:	alks_MarketableSecuritiesRealizedGain
Namespace Prefix:	alks_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Represents the loss realized on the sale of debt or equity securities categorized as held-to-maturity, trading securities and available-for-sale.

+ References

No definition available.

+ Details

Name:	alks_MarketableSecuritiesRealizedLoss
Namespace Prefix:	alks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- References

No definition available.

+ Details

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

X

- Definition

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

+ References

No definition available.

+ Details

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