Common and Preferred Stock Preferred Stock Issuance (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Jun. 19, 2014
Preferred Stock Issuance [Abstract]
Depositary shares issued	6,000,000
Preferred stock, shares issued	6,000	6,000	6,000
Preferred stock, par value	$ 1.00	$ 1.00	$ 1.00
Preferred Stock, Liquidation Preference, Value	$ 150.0
Preferred Stock, Liquidation Preference Per Share	$ 25