Earnings Per Share, Textuals (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
	Jul. 01, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Potential dilutive effect of options and Warrants
Options outstanding to purchase common shares		16,645		16,645		16,645
Average exercise price per share		$ 80.01		$ 80.01		$ 80.01
Add: dilutive effect of warrants		939,000	505,000	0	490,000
Dividends
Cash dividends paid				$ 14.0	$ 12.8
Cash dividends paid per share				$ 0.80	$ 0.70
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Repurchase of common stock		552,454			346,781
Weighted-average price per share of common stock repurchased		$ 75.21			$ 69.25
Repurchase of common stock, total cost		$ 41.5		$ 41.5	$ 24.0
Common share amount available for additional share repurchase		$ 131.2		$ 131.2
Warrant Transactions
Potential dilutive effect of options and Warrants
Number of common shares underlying the Warrants outstanding		3,700,000		3,700,000
Average exercise price of common shares underlying Warrants		$ 60.44		$ 60.44
Warrant Transactions
Potential dilutive effect of options and Warrants
Number of common shares underlying the Warrants outstanding			3,600,000		3,600,000	3,600,000
Average exercise price of common shares underlying Warrants			$ 60.89		$ 60.89
Warrants [Member]
Potential dilutive effect of options and Warrants
Add: dilutive effect of warrants		939,221	505,151
Subsequent Event [Member]
Potential dilutive effect of options and Warrants
Trading days warrants are exercisable	120 days