Equipment held for lease - Summary of fixed and variable operating lease revenues (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating Leases Lease Income [Abstract]
Fixed lease revenue	$ 1,105	$ 1,062	$ 2,167	$ 2,158
Variable lease revenue	342	99	604	431
Total	$ 1,447	$ 1,161	$ 2,771	$ 2,589