Regulatory Capital (Details)		9 Months Ended	12 Months Ended
Jan. 01, 2019	Sep. 30, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio: Actual Ratio		9.74%	9.37%
CET1: Actual Ratio		11.15%	10.81%
Tier I risk-based capital ratio: Actual Ratio		12.00%	11.75%
Total risk--based capital ratio: Actual Ratio		13.25%	12.87%
Leverage ratio: For Capital Adequacy Purposes Ratio		4.00%	4.00%
CET1: For Capital Adequacy Purposes Ratio		6.375%	5.75%
Tier I risk-based capital ratio: For Capital Adequacy Purposes Ratio		7.875%	7.25%
Total risk-based capital ratio: For Capital Adequacy Purposes Ratio		9.875%	9.25%
Capital conservation buffer		1.875%	1.25%
Scenario, Forecast
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio: For Capital Adequacy Purposes Ratio	4.00%
CET1: For Capital Adequacy Purposes Ratio	7.00%
Tier I risk-based capital ratio: For Capital Adequacy Purposes Ratio	8.50%
Total risk-based capital ratio: For Capital Adequacy Purposes Ratio	10.50%
Capital conservation buffer	2.50%
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio: Actual Ratio		9.35%	9.03%
CET1: Actual Ratio		11.52%	11.33%
Tier I risk-based capital ratio: Actual Ratio		11.52%	11.33%
Total risk--based capital ratio: Actual Ratio		12.77%	12.50%
Leverage ratio: To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio		5.00%	5.00%
CET1: To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio		6.50%	6.50%
Tier I risk-based capital ratio: To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio		8.00%	8.00%
Total risk-based capital ratio: To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio		10.00%	10.00%

Capital Conservation Buffer

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Common Equity Tier One Capital Required To Be Well Capitalized To Risk Weighted Assets

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Common Equity Tier One Capital To Risk Weighted Assets

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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