Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Revenues	$ 2,027,907	$ 1,502,909	$ 1,363,512	$ 920,730	$ 1,855,451	$ 1,269,934	$ 1,115,557	$ 928,566	$ 5,815,058	$ 5,169,508	$ 4,171,248
Cost of revenues									4,562,303	4,144,065	3,269,270
Selling, general and administrative									607,819	535,382	455,108
Total									5,170,122	4,679,447	3,724,378
Income from operations									644,936	490,061	446,870
Other:
Income (loss) from unconsolidated entities									116,066	40,748	21,119
Other income - net									53,309	58,218	67,573
Income before income taxes	301,747	203,574	199,209	109,781	168,160	163,653	140,397	116,817	814,311	589,027	535,562
Income tax provision									278,816	206,932	172,395
Net income	$ 191,878	$ 148,563	$ 124,638	$ 70,416	$ 114,378	$ 105,483	$ 89,054	$ 73,180	535,495	382,095	363,167
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other comprehensive income (loss), net of tax									1,426	(827)	329
Total comprehensive income									$ 536,921	$ 381,268	$ 363,496
Income per share:
Basic	$ 1.20	$ 0.91	$ 0.76	$ 0.43	$ 0.70	$ 0.64	$ 0.53	$ 0.42	$ 3.30	$ 2.27	$ 2.06
Diluted	$ 1.17	$ 0.87	$ 0.73	$ 0.42	$ 0.67	$ 0.61	$ 0.51	$ 0.40	$ 3.17	$ 2.18	$ 1.97
Weighted average number of shares:
Basic	159,232	163,478	163,492	162,588	163,970	165,919	168,952	174,205	162,222	168,261	176,425
Diluted	164,565	171,562	171,403	170,417	171,683	173,405	176,414	182,391	169,487	175,973	184,703