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Income Taxes - Statutory to Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory tax rate	35.00%	35.00%	35.00%
Low income housing tax credits	(2.90%)	(3.80%)	(4.40%)
Tax-exempt interest	(4.00%)	(4.40%)	(4.10%)
Bank owned life insurance	(0.80%)	(0.80%)	(0.80%)
Other	0.30%	0.20%	1.00%
Adjustment to net deferred tax assets for enacted changes in tax laws and rates	11.30%	0.00%	0.00%
Effective Tax Rate	38.90%	26.20%	26.70%

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Other non-taxable income

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the income tax rates.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other nondeductible expenses.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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