Earnings Per Share, Textuals (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended
	Apr. 30, 2013	Jun. 30, 2008	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Potential dilutive effect of options and Warrants
Options outstanding to purchase common shares			20,791	20,791		20,791
Average exercise price per share			$ 80.01	$ 80.01		$ 80.01
Potential dilutive effect of options outstanding				0		0
Dividends
Cash dividends paid				$ 17.3	$ 14.7
Cash dividends paid per share			$ 0.30	$ 0.90	$ 0.75
Receipts of cash dividends from distribution of bankruptcy trust				0.6	0
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Stock repurchase program, authorized amount by Board of Directors	75.0	75.0
Common share amount available for additional share repurchase				78.0		46.9
Repurchase of common stock				707,077
Weighted-average price per share of common stock repurchased				$ 62.14
Repurchase of common stock				$ 43.9
Warrant Transactions
Potential dilutive effect of options and Warrants
Number of common shares underlying the Warrants outstanding			3,600,000	3,600,000
Average exercise price of common shares underlying Warrants			61.14	61.14	61.32
Common Stock
Dividends
Shares returned from distribution of bankruptcy trust, shares				9,001
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Repurchase of common stock				707,077