Fair Values Disclosures - Changes in Level 3 Assets and Liabilities Measured at Fair Value (Details) - Level 3 - Measurement of fair value on a recurring basis - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest Rate Lock Commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation
Asset (liability) balance, beginning of period	$ 223	$ 297	$ 716
Total net gains (losses) included in net income	401	(74)	(419)
Total net gains (losses) included in other comprehensive income (loss)	0	0	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	0	0	0
Asset (liability) balance, end of period	624	223	297
Other Contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation
Asset (liability) balance, beginning of period	(615)	(619)	(305)
Total net gains (losses) included in net income	(274)	(310)	(629)
Total net gains (losses) included in other comprehensive income (loss)	0	0	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	306	314	315
Asset (liability) balance, end of period	(583)	(615)	(619)
Forward Loan Sales Commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation
Asset (liability) balance, beginning of period	63	361	265
Total net gains (losses) included in net income	(89)	(298)	96
Total net gains (losses) included in other comprehensive income (loss)	0	0	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	0	0	0
Asset (liability) balance, end of period	(26)	63	361
Debt Securities Available for Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset (liability) balance, beginning of period	6	18	34
Total net gains (losses) included in net income	0	0	0
Total net gains (losses) included in other comprehensive income (loss)	0	0	0
Sales	0	0	0
Originations	0	0	0
Principal paydowns / settlements	(2)	(12)	(16)
Asset (liability) balance, end of period	4	6	18
Loans Held for Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset (liability) balance, beginning of period	3,356	6,498	10,568
Total net gains (losses) included in net income	454	129	(48)
Total net gains (losses) included in other comprehensive income (loss)	0	0	0
Sales	(332,288)	(215,381)	(343,949)
Originations	346,560	212,509	339,930
Principal paydowns / settlements	(12)	(399)	(3)
Asset (liability) balance, end of period	18,070	3,356	6,498
Interest-only Strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Asset (liability) balance, beginning of period	21,386	40,152	44,332
Total net gains (losses) included in net income	2,616	3,939	2,980
Total net gains (losses) included in other comprehensive income (loss)	1,195	(452)	159
Sales	0	0	0
Originations	4,797	3,377	22,620
Principal paydowns / settlements	(13,159)	(25,630)	(29,939)
Asset (liability) balance, end of period	$ 16,835	$ 21,386	$ 40,152

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of gain (loss) recognized in the income statement 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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