Repurchase Agreements - Additional Information (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) counterparty	Dec. 31, 2018 USD ($) counterparty
Concentration Risk [Line Items]
Number of counterparties with master repurchase agreements	49	48
Repurchase agreements, carrying amount \| $	$ 11,354,547	$ 7,037,651
Number of counterparties with repurchase agreements outstanding	25	23
Counterparty Concentration Risk \| Repurchase Agreement Borrowings
Concentration Risk [Line Items]
Number of counterparties	2	1
Counterparty Concentration Risk \| Stockholders' Equity, Total
Concentration Risk [Line Items]
Percentage of concentration risk	12.70%
Counterparty Concentration Risk \| Repurchase Agreement Borrowings
Concentration Risk [Line Items]
Percentage of concentration risk		6.80%
Counterparty Concentration Risk \| BUCKLER Securities, LLC \| Repurchase Agreement Borrowings
Concentration Risk [Line Items]
Percentage of concentration risk	45.00%	49.80%
Counterparty Concentration Risk \| BUCKLER Securities, LLC \| Stockholders' Equity, Total
Concentration Risk [Line Items]
Percentage of concentration risk	14.80%	13.00%
Weighted average maturity	7 days	14 days
Maximum
Concentration Risk [Line Items]
Ratio of indebtedness to net capital	12
Maximum \| Counterparty Concentration Risk \| Repurchase Agreement Borrowings
Concentration Risk [Line Items]
Percentage of concentration risk	10.00%	10.00%
Minimum \| Counterparty Concentration Risk \| Repurchase Agreement Borrowings
Concentration Risk [Line Items]
Percentage of concentration risk	5.00%	5.00%

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Repurchase Agreements, Number of Counterparties with Master Repurchase Agreements

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Carrying amount of assets sold under agreements to repurchase when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under repurchase agreements exceeds 10 percent of total assets.

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Indebtedness divided by net capital.

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