Commitments and contingencies (Details 2) (License agreement., USD $)	12 Months Ended
Dec. 31, 2014
License agreement
Milestone minimum annual payment	$ 50,000espr_MilestonesMinimumAnnualPayment
Maximum
License agreement
Number of shares of common stock to be issued upon meeting various future milestones	11,451

Represents the number of shares of common stock that the entity is contractually obligated to issue upon meeting various future milestones.

No definition available.

Name:	espr_NumberOfSharesOfCommonStockToBeIssuedUponMeetingVariousFutureMilestones
Namespace Prefix:	espr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration