Common Stock Preferred Stock Issuance (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Preferred Stock Issuance [Abstract]
Depositary preferred shares issued	6,000,000
Preferred stock, shares issued	6,000	0
Preferred stock, par value	$ 1.00	$ 1.00
Preferred Stock, Liquidation Preference, Value	$ 150,000,000
Preferred Stock, Liquidation Preference Per Share	$ 25
Proceeds from issuance of preferred stock	144,784,000	0	0
Preferred Stock Dividends, Income Statement Impact	$ 4,050,000	$ 0	$ 0