Note 6 - Net Income (Loss) Per Common Share (Details Textual)	3 Months Ended
Mar. 31, 2019
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Performance Award of Initial Units Granted, Percent	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Performance Award of Initial Units Granted, Percent	250.00%

Represents the performance award of initial units granted, percent.

No definition available.

Name:	gdp_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceAwardOfInitialUnitsGrantedPercent
Namespace Prefix:	gdp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration