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Stockholders' Equity - Summary of Preferred and Common Stock (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Series B 7.5% Fixed Non-Cumulative Perpetual Preferred Stock
Class Of Stock [Line Items]
Preferred stock, dividend rate, percentage	7.50%	7.50%

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The percentage rate used to calculate dividend payments on preferred stock.

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