Equipment held for lease - Summary of operating lease revenues by type (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Leases Lease Income [Abstract]
Fixed lease revenue	$ 1,062	$ 1,118	$ 2,158	$ 2,192
Variable lease revenue	99	373	431	735
Total	$ 1,161	$ 1,491	$ 2,589	$ 2,927