Earnings per Common Share - Textual (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended			3 Months Ended		6 Months Ended							0 Months Ended	1 Months Ended		6 Months Ended
	May 01, 2014	Apr. 30, 2014	Feb. 28, 2014	Jan. 31, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Apr. 02, 2014	Jan. 16, 2014	Jan. 03, 2014	Dec. 31, 2013	Jan. 31, 2004	Jul. 17, 2014 Subsequent Event [Member]	Feb. 28, 2014 Common Stock	Oct. 31, 2013 Common Stock	Jun. 30, 2014 Common Stock	Jun. 30, 2014 2.00% Convertible Senior Subordinated Notes due 2043 [Member]	Apr. 02, 2014 2.00% Convertible Senior Subordinated Notes due 2043 [Member]	Jan. 31, 2004 Convertible Debenture [Member]
Earnings per Common Share (Textual) [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share							100,000	1,200,000
Stock Repurchase Program, Authorized Amount															$ 250	$ 200
Repurchase of common stock, Shares																	1,300,000
Repurchase of common stock																	43.1
Cash dividends per common share	$ 0.18		$ 0.18		$ 0.18	$ 0.00	$ 0.36	$ 0.00						$ 0.21
Dividends Payable, Current																	16.0
Convertible Preferred Stock, Conversion Price					$ 30.50		$ 30.50		$ 30.01		$ 30.17
Convertible Preferred Stock, Shares Issued upon Conversion					32.7869		32.7869		33.3222		33.1455
Debt Instrument, Convertible, Conversion Price																		$ 39.65	$ 39.23
Debt Instrument, Convertible, Terms of Conversion Feature																		25.2194 shares per $1,000 principal amount
Common Stock, Dividends, Per Share, Cash Paid		$ 0.18		$ 0.18										$ 0.18
Debt Instrument, Convertible, Shares Issued Upon Conversion																			25.4896
Debt Instrument, Interest Rate, Stated Percentage																				3.25%
Class of Warrant or Right, Outstanding										0		2,900,000	10,000,000
Stock warrants exercised, Shares																	200,000
Proceeds from exercise of stock warrants							$ 6.3