Fair Values Measurements - Changes in Level 3 Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest-only strips
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	$ 16,835	$ 21,386	$ 40,152
Total net gains (losses) included in:
Net income	2,568	2,616	3,939
Other comprehensive income (loss)	(262)	1,195	(452)
Acquired	0
Sales	0	0	0
Originations	2,789	4,797	3,377
Principal paydowns / settlements	(9,117)	(13,159)	(25,630)
Transfers out of Level 3	0
Asset (liability) balance, end of period	12,813	16,835	21,386
Interest rate lock commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	624	223	297
Total net gains (losses) included in:
Net income	778	401	(74)
Other comprehensive income (loss)	0	0	0
Acquired	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	0	0	0
Transfers out of Level 3	(1,402)
Asset (liability) balance, end of period	0	624	223
Swap agreement
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	(583)	(615)	(619)
Total net gains (losses) included in:
Net income	(68)	(274)	(310)
Other comprehensive income (loss)	0	0	0
Acquired	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	295	306	314
Transfers out of Level 3	0
Asset (liability) balance, end of period	(356)	(583)	(615)
Forward loan sales commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	(26)	63	361
Total net gains (losses) included in:
Net income	(119)	(89)	(298)
Other comprehensive income (loss)	0	0	0
Acquired	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	0	0	0
Transfers out of Level 3	145
Asset (liability) balance, end of period	0	(26)	63
Investment securities available-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset balance, beginning of period	4	6	18
Total net gains (losses) included in:
Net income	1	0	0
Other comprehensive income (loss)	(21)	0	0
Acquired	450
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	(1)	(2)	(12)
Transfers out of Level 3	0
Asset balance, end of period	433	4	6
Loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset balance, beginning of period	18,070	3,356	6,498
Total net gains (losses) included in:
Net income	534	454	129
Other comprehensive income (loss)	0	0	0
Acquired	0
Sales	(164,693)	(332,288)	(215,381)
Originations	175,304	346,560	212,509
Principal paydowns / settlements	(4)	(12)	(399)
Transfers out of Level 3	(29,211)
Asset balance, end of period	$ 0	$ 18,070	$ 3,356

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Acquisitions

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Fair Value, Net Assets (Liabilities) Measured On Recurring Basis, Gain (Loss) Included In Earnings [Abstract]

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Amount of gain (loss) recognized in income from 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 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 transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value 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 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 gain (loss) recognized in other comprehensive 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 derivative asset (liability) after deduction of derivative liability (asset) out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as 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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