Summary of Operating Leases (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014
Summary of operating leases
2014	$ 270,004
2015	261,108
2016	235,492
2017	218,042
2018	203,096
and thereafter	438,232
Operating Leases, Future Minimum Payments Due, Total	1,625,974
Aircraft Operating Leases
Summary of operating leases
2014	256,461
2015	250,488
2016	226,336
2017	211,293
2018	197,625
and thereafter	383,881
Operating Leases, Future Minimum Payments Due, Total	1,526,084
Building Land And Equipment Operating Leases
Summary of operating leases
2014	13,543
2015	10,620
2016	9,156
2017	6,749
2018	5,471
and thereafter	54,351
Operating Leases, Future Minimum Payments Due, Total	$ 99,890