Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended	9 Months Ended
	Jul. 11, 2016	Jan. 04, 2016	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Number of shares authorized to be repurchased			7,400,000	7,400,000
Purchase of treasury stock			$ 18.3	$ 113.5
Treasury Stock, Shares, Acquired			600,000	3,400,000
Treasury Stock Acquired, Average Cost Per Share			$ 30.52	$ 33.22
Common stock reissued				2,600,000
Preferred stock, par value			$ 1	$ 1	$ 1
Non-Cumulative Perpetual Preferred Stock, Series A [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Issuance of preferred stock	$ 150.0
Preferred stock, dividend rate percentage	6.25%
Preferred stock, par value	$ 1.00
Preferred stock liquidation preference per depositary share	25
Preferred stock, liquidation preference per share	$ 25,000
Eaton Partners [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions		300,000