Investments - JCP Fund V - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Aug. 31, 2018	Nov. 30, 2017
Schedule of Equity Method Investments [Line Items]
Financial instruments owned, at fair value	$ 15,195,619	$ 14,193,352
JCP Fund V
Schedule of Equity Method Investments [Line Items]
Financial instruments owned, at fair value	30,000	19,600
Unfunded portion of equity commitment to subsidiary	$ 9,700	$ 10,100
Percent of financial information presented	100.00%
Ownership percentage	35.10%	35.20%
Maximum | JCP Fund V
Schedule of Equity Method Investments [Line Items]
Total committed equity capitalization	$ 85,000	$ 85,000