Commitments - Summary of Operating Leases (Detail) $ in Thousands	Jul. 31, 2016 USD ($)
Summary of Operating Leases
2017	$ 165,199
2018	155,084
2019	137,600
2020	112,947
2021	91,297
Thereafter	114,542
Operating Leases, Future Minimum Payments Due, Total	776,669
Helicopter operating leases
Summary of Operating Leases
2017	151,557
2018	145,208
2019	129,897
2020	108,345
2021	87,336
Thereafter	83,350
Operating Leases, Future Minimum Payments Due, Total	705,693
Building, land and equipment operating leases
Summary of Operating Leases
2017	13,642
2018	9,876
2019	7,703
2020	4,602
2021	3,961
Thereafter	31,192
Operating Leases, Future Minimum Payments Due, Total	$ 70,976