Fair Value Disclosures (Fair Value Option Election Narrative) (Details) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2017 USD ($) $ / shares	Mar. 31, 2017 USD ($) director shares	Dec. 31, 2016 USD ($) shares	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Aggregate fair value of loans and other receivables on nonaccrual status		$ 253,800	$ 29,800
90 days or more past due		25,800	18,900
Securities borrowed		6,886,436	7,743,562
Securities loaned		2,522,846	2,819,132
Investment in associated company		2,122,479	2,125,098	$ 1,843,470	$ 1,757,369
Financial instruments owned trading assets, at fair value		14,606,439	14,985,237
KCG Holdings [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Changes in fair value of investments reflected as principal transactions		(4,600)		(37,300)
Securities borrowed		2,100	9,200
Securities loaned		2,200	$ 9,200
HRG [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Changes in fair value of investments reflected as principal transactions		$ 175,200		$ 17,200
Percentage of outstanding common stock owned		23.00%	23.00%
Shares owned, number | shares		46.6	46.6
Financial instruments owned trading assets, at fair value		$ 900,300	$ 725,100
Cash consideration paid for shares		$ 475,600
Revenue of investee			1,189,600		1,209,400
Net income from continuing operations of investee			2,000		9,500
Net income (loss) of investee			260,800		7,000
Net income (loss) attributable to HRG			$ 212,200		$ (33,900)
Number of directors appointed | director		2
Subsequent Event [Member] | KCG Holdings [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business acquisition, share price (in USD per share) | $ / shares	$ 20.00
KCG Holdings, Inc. [Member] | Jefferies [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Percentage of outstanding common stock owned		24.00%
KCG Holdings, Inc. [Member] | Subsequent Event [Member] | Jefferies [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Premium form sale of investment	$ 98,000