Condensed Statements of Shareholders' Equity (USD $)
In Millions, unless otherwise specified
Total
Common Stock
Additional Paid-In Capital
Accumulated Other Comprehensive Loss
Retained Earnings
Balance at Dec. 31, 2012 $ 998.4 $ 80.2 $ 856.1 $ (371.3) $ 433.4
Balance (in shares) at Dec. 31, 2012   80.2      
Net income 153.9 0 0 0 153.9
Other comprehensive income 8.2 0 0 8.2 0
Dividends paid:          
Common stock ($0.60 per share) (48.1) 0 0 0 (48.1)
Common stock repurchased and retired (in shares) (1.2) (1.2)      
Common stock repurchased and retired (28.8) (1.2) (27.6) 0 0
Common stock issued for:          
Stock options exercised (in shares) 0.4 0.4      
Stock options exercised 7.6 0.4 7.2 0 0
Other Transactions (in shares)   0.2      
Other Transactions 3.2 0.2 3.0 0 0
Stock-based compensation 2.9 0 2.9 0 0
Balance at Sep. 30, 2013 1,097.3 79.6 841.6 (363.1) 539.2
Balance (in shares) at Sep. 30, 2013   79.6      
Balance at Dec. 31, 2013 1,101.1 79.4 838.8 (365.1) 548.0
Balance (in shares) at Dec. 31, 2013   79.4      
Net income 92.9 0 0 0 92.9
Other comprehensive income 8.7 0 0 8.7 0
Dividends paid:          
Common stock ($0.60 per share) (47.4) 0 0 0 (47.4)
Common stock repurchased and retired (in shares) (1.7) (1.7)      
Common stock repurchased and retired (44.7) (1.7) (43.0) 0 0
Common stock issued for:          
Stock options exercised (in shares) 0.4 0.4      
Stock options exercised 8.6 0.4 8.2 0 0
Other Transactions (in shares)   0.1      
Other Transactions 2.0 0.1 1.9 0 0
Balance at Sep. 30, 2014 $ 1,121.2 $ 78.2 $ 805.9 $ (356.4) $ 593.5
Balance (in shares) at Sep. 30, 2014   78.2