Intangible assets and goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-lived intangible assets:
Gross carrying value	$ 1,595	$ 1,564
Accumulated amortization	(604)	(360)
Net carrying value	991	1,204
Amortization of intangible assets	269	289	$ 97
Customer relationships
Finite-lived intangible assets:
Gross carrying value	615	615
Accumulated amortization	(102)	(58)
Net carrying value	513	557
Backlog
Finite-lived intangible assets:
Gross carrying value	330	330
Accumulated amortization	(217)	(120)
Net carrying value	113	210
Technologies
Finite-lived intangible assets:
Gross carrying value	320	323
Accumulated amortization	(144)	(83)
Net carrying value	176	240
Software
Finite-lived intangible assets:
Gross carrying value	213	159
Accumulated amortization	(83)	(50)
Net carrying value	130	109
Image library
Finite-lived intangible assets:
Gross carrying value	80	80
Accumulated amortization	(48)	(32)
Net carrying value	32	48
Trade names and other
Finite-lived intangible assets:
Gross carrying value	37	37
Accumulated amortization	(10)	(5)
Net carrying value	$ 27	32
Non-compete agreements
Finite-lived intangible assets:
Gross carrying value		20
Accumulated amortization		(12)
Net carrying value		$ 8