Regulatory Capital - Well Capitalized Regulatory Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Actual Amount
Tier 1 Capital (to Average Assets)	$ 1,734,315
Tier 1 Capital (to Risk-Weighted Assets)	1,734,315	$ 1,413,988
Total Capital (to Risk-Weighted Assets)	1,848,528	1,497,830
Tier 1 Capital (to Average Assets)	$ 1,734,315	$ 1,413,988
Actual Ratio
Tier 1 Capital (to Average Assets)	14.40%
Tier 1 Capital (to Risk-Weighted Assets)	14.40%	15.00%
Total Capital (to Risk-Weighted Assets)	15.40%	15.90%
Tier 1 Capital (to Average Assets)	12.30%	11.50%
Well Capitalized Regulatory Requirements, Amount
Tier 1 Capital (to Average Assets)	$ 781,638
Tier 1 Capital (to Risk-Weighted Assets)	962,017	$ 565,148
Total Capital (to Risk-Weighted Assets)	1,202,521	941,913
Tier 1 Capital (to Average Assets)	$ 704,979	$ 614,709
Well Capitalized Regulatory Requirements, Ratio
Tier 1 Capital (to Average Assets)	6.50%
Tier 1 Capital (to Risk-Weighted Assets)	8.00%	6.00%
Total Capital (to Risk-Weighted Assets)	10.00%	10.00%
Tier 1 Capital (to Average Assets)	5.00%	5.00%

Common Equity Tier One Risk Based Capital

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Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets

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Tier One Common Equity Capital to Risk Weighted Assets

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Tier One Risk Based Capital for Common Equity Required to be Capitalized

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The amount of total capital as defined in the regulations.

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The amount of Total Capital required to be categorized as well as capitalized 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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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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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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Tier 1 Risk Based Capital as defined in the regulations.

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The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized 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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