Fair Values Measurements - 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
Interest-only Strips
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	$ 10,951	$ 16,163	$ 12,813	$ 16,835
Total net gains (losses) included in:
Net income	327	653	486	1,365
Other comprehensive income (loss)	1,989	25	1,641	311
Sales		0		0
Originations		708		1,552
Principal paydowns / settlements	(1,456)	(2,313)	(3,129)	(4,827)
Asset (liability) balance, end of period	11,811	15,236	11,811	15,236
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	1,989	25	1,641	311
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	0	1,117	0	624
Total net gains (losses) included in:
Net income	0	285	0	778
Other comprehensive income (loss)	0	0	0	0
Sales		0		0
Originations		0		0
Principal paydowns / settlements	0	0	0	0
Asset (liability) balance, end of period	0	1,402	0	1,402
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	0	0	0	0
Swap agreement
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Asset (liability) balance, beginning of period	(286)	(510)	(356)	(583)
Total net gains (losses) included in:
Net income	0	0	(1)	0
Other comprehensive income (loss)	0	0	0	0
Sales		0		0
Originations		0		0
Principal paydowns / settlements	73	75	144	148
Asset (liability) balance, end of period	(213)	(435)	(213)	(435)
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	0	0	0	0
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	0	(118)	0	(26)
Total net gains (losses) included in:
Net income	0	(27)	0	(119)
Other comprehensive income (loss)	0	0	0	0
Sales		0		0
Originations		0		0
Principal paydowns / settlements	0	0	0	0
Asset (liability) balance, end of period	0	(145)	0	(145)
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	0	0	0	0
Investment securities available-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset balance, beginning of period	403	4	433	4
Total net gains (losses) included in:
Net income	1	0	2	0
Other comprehensive income (loss)	37	0	6	0
Sales		0		0
Originations		0		0
Principal paydowns / settlements	0	(1)	0	(1)
Asset balance, end of period	441	3	441	3
Total net gains (losses) included in:
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	37	0	6	0
Loans Held for Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset balance, beginning of period	0	9,863	0	18,070
Total net gains (losses) included in:
Net income	0	700	0	534
Other comprehensive income (loss)	0	0	0	0
Sales		(91,255)		(164,693)
Originations		109,904		175,304
Principal paydowns / settlements	0	(1)	0	(4)
Asset balance, end of period	0	29,211	0	29,211
Total net gains (losses) included in:
Unrealized gains (losses) included in other comprehensive income for assets held at the end of the period	$ 0	$ 0	$ 0	$ 0

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

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Unrealized Holding Gain (Loss) Transfers from Available for Sale to Held to Maturity Retained in Accumulated Other Comprehensive Income

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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 gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances 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 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 settlement 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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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 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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