Borrowings (Tables)

12 Months Ended

Dec. 31, 2019

Debt Instrument [Line Items]

Outstanding borrowings and financing capacity or unused available capacity under the Company’s borrowing arrangements

The following summarizes the Company’s broker-dealer credit facilities' carrying values, net of unamortized debt issuance costs, where applicable. These balances are included within Short-term borrowings on the Consolidated Statement of Financial Condition.

	At December 31, 2019
(in thousands)	Interest Rate	Financing Available		Borrowing Outstanding		Deferred Debt Issuance Cost			Outstanding Borrowings, net
Broker-dealer credit facilities:
Uncommitted facility	2.55%	$	200,000	$	30,000	$	(2,100	)	$	27,900
Committed facility	3.01%	600,000		—		—			—
		$	800,000	$	30,000	$	(2,100	)	$	27,900

	At December 31, 2018
(in thousands)	Interest Rate	Financing Available		Borrowing Outstanding		Deferred Debt Issuance Cost			Outstanding Borrowings, net
Broker-dealer credit facilities:
Uncommitted facility	3.40%	$	200,000	$	10,000	$	(832	)	$	9,168
Committed facility	3.75%	500,000		7,000		(1,040		)	5,960
		$	700,000	$	17,000	$	(1,872	)	$	15,128

Schedule of interest expense on debt

The following summarizes interest expense for the broker-dealer facilities. Interest expense is included within Interest and dividends expense in the accompanying Consolidated Statements of Comprehensive Income.

	Years Ended December 31,
(in thousands)	2019		2018		2017
Broker-dealer credit facilities:
Uncommitted facility	$	1,591	$	1,794	$	1,667
Committed facility	454		306		52
	$	2,045	$	2,100	$	1,719

Schedule of aggregate future required principal payments based on terms of loan

As of December 31, 2019, aggregate future required minimum principal payments based on the terms of the long-term borrowings were as follows:

(in thousands)	December 31, 2019
2020	15,000
2021	15,000
2022	15,000
2023	47,225
2024	15,000
Thereafter	1,850,000
Total principal of long-term borrowings	$	1,957,225

Short-Term Credit Facilities

Debt Instrument [Line Items]

Schedule of reconciliation of the senior secured credit facility

The proceeds of these facilities are used to meet margin requirements associated with the products traded by the Company in the ordinary course, and amounts borrowed are collateralized by the Company’s trading accounts with the applicable financial institution.

	At December 31, 2019
	Weighted Average Interest Rate	Financing Available		Borrowing Outstanding
Short-Term Credit Facilities:
Short-term credit facilities (1)	4.22%	$	586,000	$	134,331
		$	586,000	$	134,331

	At December 31, 2018
	Weighted Average Interest Rate	Financing Available		Borrowing Outstanding
Short-Term Credit Facilities:
Short-term credit facilities (1)	5.03%	$	566,000	$	184,608
		$	566,000	$	184,608

(1)   Outstanding borrowings are included with Receivables from/ Payables to broker-dealers and clearing organizations within the Consolidated Statements of Financial Condition.

Senior Secured Credit Facility

Debt Instrument [Line Items]

Schedule of reconciliation of the senior secured credit facility

The following summarizes the Company’s long-term borrowings, net of unamortized discount and debt issuance costs, where applicable:

		At December 31, 2019
(in thousands)	Maturity Date	Interest Rate	Outstanding Principal		Discount			Deferred Debt Issuance Cost			Outstanding Borrowings, net
Long-term borrowings:
First Lien Term Loan Facility	March 2026	5.20%	$	1,925,000	$	(6,795	)	$	(32,513	)	$	1,885,692
SBI bonds	January 2023	5.00%	32,225		—			(51		)	32,174
			$	1,957,225	$	(6,795	)	$	(32,564	)	$	1,917,866

		At December 31, 2018
(in thousands)	Maturity Date	Interest Rate	Outstanding Principal		Discount			Deferred Debt Issuance Cost			Outstanding Borrowings, net
Long-term borrowings:
Fourth Amended and Restated Credit Facility	December 2021	5.55%	$	400,000	$	(332	)	$	(6,704	)	$	392,964
Senior Secured Second Lien Notes	June 2022	6.75%	500,000		—			(17,811		)	482,189
SBI bonds	January 2020	5.00%	31,908		—			(24		)	31,884
			$	931,908	$	(332	)	$	(24,539	)	$	907,037