Fair Value Measurements - Narrative (Details) - Impaired_Asset_And_Liabilty	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Number of non-financial assets and liabilities impaired	0	0	0

Represents the number of non-financial assets and liabilities that were impaired during the period.

No definition available.

Name:	cog_NumberOfNonFinancialAssetsAndLiabilitiesImpaired
Namespace Prefix:	cog_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration