Stockholders’ Equity - Dividend Rights (Details) - Common Stock	9 Months Ended
Sep. 30, 2018 USD ($) Vote / shares
Dividends Rights
No dividends declared \| $	$ 0
Voting Rights
Common stock, vote per share \| Vote / shares	1

Represents the voting rights per share for common stock of the entity.

No definition available.

Name:	gemp_CommonStockVotingRightsPerShare
Namespace Prefix:	gemp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration