Regulatory Capital - Well Capitalized Regulatory Requirements (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Actual
Tier I Capital (to Average Assets)	$ 1,639,235	$ 1,413,988
Tier I Capital (to Risk-Weighted Assets)	1,639,235	1,413,988
Total Capital (to Risk-Weighted Assets)	1,743,438	$ 1,497,830
Common Equity Tier I Capital (to Risk-Weighted Assets)	$ 1,639,235
Actual Ratio
Tier I Capital (to Average Assets)	12.20%	11.50%
Tier I Capital (to Risk-Weighted Assets)	13.30%	15.00%
Total Capital (to Risk-Weighted Assets)	14.10%	15.90%
Common Equity Tier I Capital (to Risk-Weighted Assets)	13.30%
Well Capitalized Regulatory Requirements, Amount
Tier I Capital (to Average Assets)	$ 674,490	$ 614,709
Tier I Capital (to Risk-Weighted Assets)	989,333	565,148
Total Capital (to Risk-Weighted Assets)	1,236,667	$ 941,913
Common Equity Tier I Capital (to Risk-Weighted Assets)	$ 803,833
Well Capitalized Regulatory Requirements, Ratio
Tier I Capital (to Average Assets)	5.00%	5.00%
Tier I Capital (to Risk-Weighted Assets)	8.00%	6.00%
Total Capital (to Risk-Weighted Assets)	10.00%	10.00%
Common Equity Tier I Capital (to Risk-Weighted Assets)	6.50%

Common Equity Capital Required to Be Well Capitalized Percent

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Common Equity Tier 1 to Risk Weighted Assets

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common equity tier 1 capital

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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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