Earnings Per Share, Textuals (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Potential dilutive effect of options and Warrants
Options outstanding to purchase common shares	18,606		20,791
Average exercise price per share	$ 80.01		$ 80.01
Dividends
Cash dividends paid	$ 19.1	$ 17.3
Cash dividends paid per share	$ 1.05	$ 0.90
Receipts of cash dividends from distribution of bankruptcy trust	0	0.6
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Repurchase of common stock	410,589	707,077
Weighted-average price per share of common stock repurchased	$ 70.34	$ 62.14
Repurchase of common stock, total cost	28.9	43.9
Common share amount available for additional share repurchase	$ 88.7		$ 117.6
Warrant Transactions
Potential dilutive effect of options and Warrants
Number of common shares underlying the Warrants outstanding	3,700,000	3,600,000
Average exercise price of common shares underlying Warrants	60.80	61.14