Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Nov. 30, 2016 Container	Jun. 30, 2018 Container Tractor Trailer	Jun. 30, 2018 USD ($) Tractor Trailer
Commitments And Contingencies Disclosure [Abstract]
Purchase contract units, containers | Container	4,000	3,670
Purchase contract units tractors | Tractor			869
Cost of purchasing tractors | $			$ 107.2
Number of tractors received | Tractor		380	380
Number of tractors expected to be received in remainder of fiscal year | Tractor		489	489
Purchase contract units trailers | Trailer			760
Cost of purchasing trailers | $			$ 24.2
Number of trailers received | Trailer		217	217
Number of trailers expected to be received in remainder of fiscal year | Trailer		543	543