Organization and Significant Accounting Policies, Stock-Based Compensation Expense (Details)	12 Months Ended
Dec. 31, 2021 Period $ / shares shares	Dec. 31, 2020 $ / shares
RSUs [Member] \| Employees [Member]
Stock-Based Compensation Expense [Abstract]
Vesting period	4 years
RSUs [Member] \| Board of Directors [Member] \| Granted Prior to June 2020 [Member]
Stock-Based Compensation Expense [Abstract]
Vesting period	4 years
RSUs [Member] \| Board of Directors [Member] \| Granted After June 2020 [Member]
Stock-Based Compensation Expense [Abstract]
Vesting period	1 year
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member]
Stock-Based Compensation Expense [Abstract]
Number of performance periods \| Period	3
Vesting period	3 years
Number of units guaranteed to vest \| shares	0
Weighted-average grant date fair value (in dollars per share) \| $ / shares	$ 77.17	$ 93.09
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member] \| Minimum [Member]
Stock-Based Compensation Expense [Abstract]
Percentage of units guaranteed to vest	0.00%
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member] \| Maximum [Member]
Stock-Based Compensation Expense [Abstract]
Percentage of units guaranteed to vest	150.00%
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member] \| One-Year Period [Member]
Stock-Based Compensation Expense [Abstract]
Vesting percentage	33.30%
Vesting period	1 year
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member] \| Two-Year Period [Member]
Stock-Based Compensation Expense [Abstract]
Vesting percentage	33.30%
Vesting period	2 years
PRSUs [Member] \| Chief Executive Officer, Dr. Brett Monia [Member] \| Three-Year Period [Member]
Stock-Based Compensation Expense [Abstract]
Vesting percentage	33.30%
Vesting period	3 years

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Number of units guaranteed to vest under share-based payment arrangement.

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Percentage of units guaranteed to vest under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Percentage of vesting of award under share-based payment arrangement.

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