Earnings Per Share, Other Disclosures (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Mar. 30, 2010
Potential dilutive effect of options and Warrants
Options outstanding to purchase common shares		16,645		20,791
Average exercise price per share		$ 80.01		$ 80.01
Potential dilutive effect of shares underlying the options				0		0
Dividends
Payment of cash dividends to stockholders		$ 25.4	[1]	$ 23.0	[1]	$ 19.6	[1]
Payment of quarterly cash dividends		$ 1.40		$ 1.20		$ 1.00
Cash dividend returned to the Company	0.6	0	[1]	0.6	[1]	0	[1]
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Shares returned from distribution of bankruptcy trust, shares				9,001
Repurchase of common shares pursuant to an authorization from the Board, shares		633,230		1,232,077		0
Weighted-average price of repurchases of common shares		$ 70.87		$ 64.35
Repurchase of common shares pursuant to an authorization from the Board, value		44.9		79.3
Common shares available for additional share repurchase		$ 72.8		$ 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				3,700,000
Average exercise price of common shares underlying warrants		$ 60.70		$ 61.08
Common Stock
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Shares returned from distribution of bankruptcy trust, shares	9,001
Repurchase of common shares pursuant to an authorization from the Board, shares		633,230		1,232,077

[1] See Note 14 for the supplemental disclosure on non-cash transactions.