Consolidated Statements of Stockholders' Equity (Unaudited) (USD $)
In Millions
Total
Common Stock [Member]
Additional Paid-In Capital [Member]
Treasury Stock [Member]
Retained Earnings [Member]
Accumulated Other Comprehensive Income [Member]
Balance at Dec. 31, 2011 $ 446.6 $ 0.4 $ 37.4 $ (4.5) $ 372.5 $ 40.8
Dividends on common stock (33.2)       (33.2)  
Shares issued for restricted stock units 0   (0.1) 0.1    
Stock options exercised 1.5   1.4 0.1    
Income tax benefits from equity awards 0.8   0.8      
Stock-based compensation 3.6   3.6      
Comprehensive income 54.1       49.4 4.7
Balance at Jun. 30, 2012 $ 473.4 $ 0.4 $ 43.1 $ (4.3) $ 388.7 $ 45.5