CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
CONSOLIDATED STATEMENTS OF CASH FLOWS
Cash settlements on derivatives (including $56.6 million and $51.3 million on commodity hedges during 2016 and 2015)	$ 56.6	$ 51.3

Represents the amount of cash settlements on commodity derivatives

No definition available.

Name:	kos_CashSettlementsOnCommodityDerivatives
Namespace Prefix:	kos_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration