Properties and Equipment, Net (Details 2)	3 Months Ended
Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Minimum term of capitalization of exploratory well costs	1 year

Represents the term of capitalization used for aging disclosure.

No definition available.

Name:	cog_CapitalizedExploratoryWellPeriodofCapitalization
Namespace Prefix:	cog_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration