Organization and Significant Accounting Policies, Organization and Business Activity (Details)	Dec. 31, 2017
Ionis [Member] \| Akcea [Member]
Organization and Business Activity [Abstract]
Ownership percentage by majority shareholder	68.00%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

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