Stockholders? Equity - Dividend Rights (Details) - Common Stock	6 Months Ended	12 Months Ended
Jun. 30, 2019 USD ($) Vote / shares	Dec. 31, 2018 USD ($) Vote / shares
Dividends Rights
No dividends declared \| $	$ 0	$ 0
Voting Rights
Common stock, vote per share \| Vote / shares	1	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