Organization and Significant Accounting Policies, Contracts Receivable (Details)	12 Months Ended
Dec. 31, 2020
Contracts Receivable [Abstract]
Period of time after billing when payment is received	3 months

The time period between billing a collaboration partner for goods delivered or services performed that are due unconditionally and payment is received from the collaboration partner, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ions_PeriodAfterBillingWhenPaymentIsReceived
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration