Shareholders' Equity, Capital Ratios and Other Regulatory Matters (Details)	3 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 $ / shares
Class of Stock
Preferred stock, par value (in usd per share)	$ 1	$ 1
Liquidation preference (per share)	$ 10,000	$ 10,000
Series B Preferred Stock
Class of Stock
Depositary shares issued | shares	3,200,000
Depository shares to preferred stock ratio	0.0025
Non-cumulative preferred stock, dividend rate	6.625%
Preferred stock, par value (in usd per share)	$ 1
Liquidation preference (per share)	$ 10,000
Depositary share issue price	25
Aggregate liquidation preference | $	$ 80,000,000
Series B Preferred Stock | Three-month LIBOR Rate
Class of Stock
Floating rate basis spread	4.262%