Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016
Revenues	$ 2,455,238	$ 1,913,353	$ 1,599,199	$ 1,175,468	$ 2,027,907	$ 1,502,909	$ 1,363,512	$ 920,730	$ 7,143,258	$ 5,815,058	$ 5,169,508
Cost of revenues									5,673,007	4,562,303	4,144,065
Selling, general and administrative									684,035	605,572	533,118
Total									6,357,042	5,167,875	4,677,183
Income from operations									786,216	647,183	492,325
Other:
Income (loss) from unconsolidated entities									85,240	116,066	40,748
Other income - net									62,460	51,062	55,954
Income before income taxes	396,473	253,097	152,748	131,598	301,747	203,574	199,209	109,781	933,916	814,311	589,027
Income tax provision									185,765	278,816	206,932
Net income	$ 310,976	$ 193,258	$ 111,810	$ 132,107	$ 191,878	$ 148,563	$ 124,638	$ 70,416	748,151	535,495	382,095
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other comprehensive income (loss), net of tax									2,926	1,426	(827)
Total comprehensive income									$ 751,077	$ 536,921	$ 381,268
Income per share:
Basic	$ 2.10	$ 1.28	$ 0.73	$ 0.85	$ 1.20	$ 0.91	$ 0.76	$ 0.43	$ 4.92	$ 3.30	$ 2.27
Diluted	$ 2.08	$ 1.26	$ 0.72	$ 0.83	$ 1.17	$ 0.87	$ 0.73	$ 0.42	$ 4.85	$ 3.17	$ 2.18
Weighted average number of shares:
Basic	148,066	151,257	152,731	155,882	159,232	163,478	163,492	162,588	151,984	162,222	168,261
Diluted	149,603	153,173	155,129	158,897	164,565	171,562	171,403	170,417	154,201	169,487	175,973