Intangible assets (Tables)

12 Months Ended

Dec. 31, 2018

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Summary by Class of Assets

13.1. By class of assets

				Software
	Rights and Concessions			Acquired			Developed in-house			Goodwill			Total
Balance at January 1, 2017		2,678			68			306			220			3,272
Addition		935			16			61			—			1,012
Capitalized borrowing costs		—			—			4			—			4
Write-offs		(81	)		—			(2	)		—			(83	)
Transfers		(1,656	)		2			—			—			(1,654	)
Amortization		(20	)		(29	)		(101	)		—			(150	)
Impairment recognition		(33	)		—			—			—			(33	)
Cumulative translation adjustment		(22	)		—			(4	)		(2	)		(28	)
Balance at December 31, 2017		1,801			57			264			218			2,340
Cost		2,006			496			1,225			218			3,945
Accumulated amortization		(205	)		(439	)		(961	)		—			(1,605	)
Balance at December 31, 2017		1,801			57			264			218			2,340
Addition		841			35			50			—			926
Capitalized borrowing costs		—			—			4			—			4
Write-offs		(15	)		—			—			—			(15	)
Transfers		(42	)		6			—			14			(22	)
Amortization		(14	)		(23	)		(75	)		—			(112	)
Cumulative translation adjustment		(241	)		(8	)		(38	)		(29	)		(316	)
Balance at December 31, 2018		2,330			67			205			203			2,805
Cost		2,549			487			1,105			203			4,344
Accumulated amortization		(219	)		(420	)		(900	)		—			(1,539	)
Balance at December 31, 2018		2,330			67			205			203			2,805
Estimated useful life in years		(	*)		5			5			Indefinite

(*) Mainly composed of assets with indefinite useful lives, which are reviewed annually to determine whether events and circumstances continue to support an indefinite useful life assessment.

Summary of Exploratory Phases

Exploration areas returned to the ANP in 2018, totaling US$ 6 (US$ 3 in 2017) are set out below:

Area	Exploratory phase
	Exclusive		Partnership
Sergipe-Alagos basin		5		—
Espirito Santo basin		2		—
Barreirinhas basin		1		—