Schedule I (PARENT COMPANY ONLY) (CONDENSED STATEMENTS OF CASH FLOWS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2014
Cash flows from operating activities:
Net earnings	$ 15,434	$ 93,534	$ 157,560
Adjustments to reconcile net earnings to net cash (used in) provided by operating activities:
Amortization	(2,365)	15,236	691
Income on loans to and investments in related parties	(17,184)	(75,717)	(90,243)
Distributions received on investments in related parties	38,180	76,681	53,985
Other adjustments	(32,711)	(97,804)	(78,064)
Net change in assets and liabilities:
Cash and securities segregated and on deposit for regulatory purposes or deposited with clearing and depository organizations	(107,771)	2,691,028	166,108
Financial instruments owned	2,529,114	2,003,978	(2,243,053)
Investments in managed funds	(138,572)	15,498	13,473
Other assets	(173,616)	(63,110)	(146,114)
Financial instruments sold, not yet purchased	1,753,647	(2,043,319)	1,832,930
Accrued expenses and other liabilities	296,067	(259,665)	48,485
Net cash used in operating activities	(122,099)	(239,387)	(27,913)
Cash flows from investing activities:
Cash received from contingent consideration	2,617	4,444	6,253
Net cash provided by (used in) investing activities	79,758	(134,612)	(277,149)
Cash flows from financing activities:
Excess tax benefits from the issuance of share-based awards	489	749	1,921
Proceeds from short-term borrowings	15,313,383	17,263,217	18,965,163
Payments on short-term borrowings	(15,108,501)	(16,964,558)	(18,965,163)
Net proceeds from issuance of senior notes, net of issuance costs	299,779	0	681,222
Repayment of long-term debt	(373,246)	(500,000)	(250,000)
Net cash provided by (used in) financing activities	86,862	(189,194)	834,305
Net increase (decrease) in cash and cash equivalents	18,906	(569,805)	518,849
Cash and cash equivalents at beginning of period	3,510,163	4,079,968	3,561,119
Cash and cash equivalents at end of period	3,529,069	3,510,163	4,079,968
Cash paid (received) during the period for:
Interest	859,466	859,815	922,194
Income taxes, net	(6,410)	(683)	120,703
Parent Company [Member]
Cash flows from operating activities:
Net earnings	15,434	93,534	157,560
Adjustments to reconcile net earnings to net cash (used in) provided by operating activities:
Amortization	(63,681)	(76,945)	(80,424)
Undistributed earnings of subsidiaries	(25,804)	(71,739)	(125,450)
Income on loans to and investments in related parties	10,251	(40,460)	(67,965)
Distributions received on investments in related parties	17,050	40,500	35,562
Other adjustments	(34,496)	(98,870)	(78,064)
Net change in assets and liabilities:
Cash and securities segregated and on deposit for regulatory purposes or deposited with clearing and depository organizations	30,055	(4,714)	(28,155)
Financial instruments owned	8,704	53,290	(45,950)
Investments in managed funds	763	19,907	(1,028)
Other assets	20,986	77,064	47,666
Financial instruments sold, not yet purchased	(13,739)	(8,802)	21,462
Accrued expenses and other liabilities	15,125	(36,397)	38,477
Net cash used in operating activities	(19,352)	(53,632)	(126,309)
Cash flows from investing activities:
Investments in, advances to and subordinated notes receivable from subsidiaries	327,110	420,797	82,143
Loans to and investments in related parties	19,337	(19,301)	(469)
Cash received from contingent consideration	2,617	4,444	6,253
Net cash provided by (used in) investing activities	349,064	405,940	87,927
Cash flows from financing activities:
Excess tax benefits from the issuance of share-based awards	489	749	1,921
Proceeds from short-term borrowings	102,238	750,000	1,160,000
Payments on short-term borrowings	(5,786)	(750,000)	(1,160,000)
Net proceeds from issuance of senior notes, net of issuance costs	277,583	0	681,222
Repayment of long-term debt	(350,000)	(500,000)	(250,000)
Net cash provided by (used in) financing activities	24,524	(499,251)	433,143
Net increase (decrease) in cash and cash equivalents	354,236	(146,943)	394,761
Cash and cash equivalents at beginning of period	824,239	971,182	576,421
Cash and cash equivalents at end of period	1,178,475	824,239	971,182
Cash paid (received) during the period for:
Interest	300,680	329,926	330,261
Income taxes, net	$ (8,654)	$ (5,859)	$ 111,542