Equity Method Investments - Summary of Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Costs and expenses:
Equity in earnings - KTIPI	$ 0	$ 24,841	$ 0	$ 59,637
Kosmos-Trident International Petroleum Inc.
Assets
Total current assets					$ 149,950
Property and equipment, net					271,627
Other assets					21
Total assets					421,598
Liabilities and stockholders' equity
Total current liabilities					226,311
Total long-term liabilities					536,178
Shareholders' equity:
Total shareholders' equity					(340,891)
Total liabilities and shareholders' equity					$ 421,598
Revenues and other income:
Oil and gas revenue		215,408		600,158
Other income		(72)		44
Total revenues and other income		215,336		600,202
Costs and expenses:
Oil and gas production		40,334		115,366
Depletion, depreciation and amortization		33,044		108,996
Other expenses, net		(58)		(211)
Total costs and expenses		73,320		224,151
Income before income taxes		142,016		376,051
Income tax expense		50,796		134,047
Net income		91,220		242,004
Kosmos' share of net income		45,610		121,002
Basis difference amortization		20,769		61,365
Equity in earnings - KTIPI		$ 24,841		$ 59,637