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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (28,970)	$ (5,645)	$ (31,540)	$ (5,645)
Net income	(19)	(4,079)	116	(4,375)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	2,444	299	4,879	595
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	(26,545)	(9,425)	(26,545)	(9,425)
Net unrealized gains/(losses) included in net income	(19)	(4,079)	116	(4,375)
Trading securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,397	1,926	1,524	2,151
Net income	8	124	29	140
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(150)	(326)	(298)	(567)
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	1,255	1,724	1,255	1,724
Net unrealized gains/(losses) included in net income	(36)	87	(66)	63
Interest- only strips- AFS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	13,195	2,733	9,902	1,270
Net income	(141)	(296)	(1,399)	1,296
Purchases	0	0	86	0
Sales	(14,199)	0	(27,211)	0
Settlements	0	0	0	(9,193)
Net transfers into/(out of) Level 3	18,937	3,350	36,414	12,414
Ending balance	17,792	5,787	17,792	5,787
Net unrealized gains/(losses) included in net income	(543)	(128)	(1,435)	(109)
Loans held- for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	15,751	18,334	16,273	18,926
Net income	321	540	816	709
Purchases	10	34	10	62
Sales	0	0	0	0
Settlements	(990)	(2,134)	(2,007)	(2,923)
Net transfers into/(out of) Level 3	0	(56)	0	(56)
Ending balance	15,092	16,718	15,092	16,718
Net unrealized gains/(losses) included in net income	$ 321	$ 542	$ 816	$ 709

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 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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