Offsetting Assets and Liabilities - Offsetting Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Offsetting Liabilities [Line Items]
Cash Collateral Pledged	$ (6,400)	$ (4,300)
Derivatives
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	30,537	19,259
Gross Amounts Offset in the Statement of Financial Condition	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Condition	30,537	19,259
Financial Instruments Collateral	0	0
Cash Collateral Pledged	(6,374)	(4,276)
Net Amount	24,163	14,983
Exchange-traded options \| Short exchange-traded options
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	12,486	12,348
Gross Amounts Offset in the Statement of Financial Condition	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Condition	12,486	12,348
Financial Instruments Collateral	0	0
Cash Collateral Pledged	0	0
Net Amount	$ 12,486	$ 12,348

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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