Fair Value of Assets & Liabilities - Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (20,890)	$ (28,970)	$ (22,795)	$ (31,540)
Net income	(201)	(19)	(712)	116
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	2,446	2,444	4,862	4,879
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	(18,645)	(26,545)	(18,645)	(26,545)
Net unrealized gains/(losses) included in net income	(201)	(19)	(712)	116
Trading securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	785	1,397	941	1,524
Net income	(157)	8	(313)	29
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(150)	0	(298)
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	628	1,255	628	1,255
Net unrealized gains/(losses) included in net income	0	(36)	0	(66)
Interest- only strips- AFS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	23,104	13,195	19,136	9,902
Net income	(1,233)	(141)	(2,528)	(1,399)
Purchases	0	0	5,481	86
Sales	0	(14,199)	(8,703)	(27,211)
Settlements	0	0	0	0
Net transfers into/(out of) Level 3	3,575	18,937	12,060	36,414
Ending balance	25,446	17,792	25,446	17,792
Net unrealized gains/(losses) included in net income	(959)	(543)	(1,813)	(1,435)
Loans held- for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	13,584	15,751	14,033	16,273
Net income	422	321	751	816
Purchases	0	10	0	10
Sales	0	0	0	0
Settlements	(743)	(990)	(1,521)	(2,007)
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	13,263	15,092	13,263	15,092
Net unrealized gains/(losses) included in net income	$ 422	$ 321	$ 751	$ 816

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Amount of unrealized gain (loss) recognized in income for derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

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Amount of purchases of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into (out of) level 3 of the fair value hierarchy.

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