Commitments and Contingencies - Additional Information (Detail) - USD ($)	Apr. 11, 2013	Aug. 01, 2012	Jul. 31, 2012	May. 17, 2012	Jul. 31, 2015	Dec. 31, 2014	Oct. 31, 2014
Loss Contingencies
Surety bonds					$ 367,500,000
Guarantee obligation					$ 91,200,000		$ 39,300,000
Subsidiary ownership interest percentage					33.00%
Loss contingency amount accrued for probable losses					$ 5,800,000
Amount of reasonably possible losses, Minimum					0
Amount of reasonably possible losses, Maximum					6,400,000
Standby Letters of Credit
Loss Contingencies
Standby letters of credit					116,100,000		$ 114,900,000
Parental
Loss Contingencies
Total guarantees					35,000,000
Contract Dispute, Work Performed by a Third Party Administrative
Loss Contingencies
Loss contingency amount accrued for probable losses					$ 2,300,000
Augustus
Loss Contingencies
Payment awarded to plaintiffs		$ 4,500,000	$ 89,700,000
Percentage of damages awarded		30.00%
Reversal of initial award						$ 89,700,000
Bojorquez
Loss Contingencies
Payment awarded to plaintiffs	$ 2,500,000			$ 800,000