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Stock-Based Compensation (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Stock-Based Compensation [Abstract]      
Number of plans 5    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expense $ 5,407 $ 4,639 $ 2,291
Total income tax benefit recognized 1,266 1,724 114
Assumptions [Abstract]      
Expected volatility, minimum (in hundredths) 49.00% 46.00% 38.00%
Expected volatility, maximum (in hundredths) 50.00% 68.00% 66.00%
Weighted-average expected volatility (in hundredths) 49.00% 46.00% 39.00%
Expected dividend yield, minimum (in hundredths) 1.70% 1.90% 2.00%
Expected dividend yield, maximum (in hundredths) 1.80% 2.50% 4.70%
Weighted-average expected dividend yield (in hundredths) 1.80% 2.40% 4.70%
Expected term, minimum (in years) 6 1 2
Expected term, maximum (in years) 6 6 6
Risk-free interest rate, minimum (in hundredths) 1.30% 0.40% 1.10%
Risk-free interest rate, maximum (in hundredths) 2.50% 2.90% 2.80%
All Plans Excluding 2010 Plan [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares reserved for issuance (in shares) 768,024    
Restricted Stock [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of new awards granted (in years) 3    
Weighted-Average Exercise Price [Abstract]      
Unrecognized compensation cost 1,327    
Compensation cost not yet recognized, weighted-average period for recognition (in years) 1.8    
Shares [Roll Forward]      
Nonvested at beginning of year (in shares) 145,641    
Granted (in shares) 29,365    
Vested (in shares) (18,152)    
Forfeited (in shares) (6,773)    
Nonvested at end of year (in shares) 150,081 145,641  
Weighted-Average Grant Date Fair Value [Abstract]      
Nonvested at beginning of year (in dollars per share) $ 24.50    
Granted (in dollars per share) $ 40.43    
Vested (in dollars per share) $ 35.83    
Forfeited (in dollars per share) $ 21.19    
Nonvested at end of year (in dollars per share) $ 26.39 $ 24.50  
Fair value of shares vested 650 284 629
Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Ratio of new awards that vest each year one-third    
Vesting period of new awards granted (in years) 3    
Contractual term of new awards (in years) 10    
Shares [Roll Forward]      
Outstanding at beginning of year (in shares) 1,402,452    
Granted (in shares) 153,936    
Exercised (in shares) (242,597)    
Forfeited (in shares) (44,871)    
Outstanding at end of year (in shares) 1,268,920 1,402,452  
Exercisable at end of year (in shares) 694,872    
Weighted-Average Exercise Price [Abstract]      
Outstanding at beginning of year (in dollars per share) $ 17.74    
Granted (in dollars per share) $ 40.28    
Exercised (in dollars per share) $ 17.51    
Forfeited (in dollars per share) $ 20.87    
Outstanding at end of year (in dollars per share) $ 20.40 $ 17.74  
Exercisable at end of year (in dollars per share) $ 17.51    
Weighted-average grant date fair value (in dollars per share) $ 16.67 $ 9.62 $ 2.59
Total intrinsic value of stock options exercised 5,600 5,235 631
Aggregate intrinsic value of options outstanding 23,646    
Aggregate intrinsic value of options exercisable 14,850    
Weighted-average remaining contractual life for options outstanding (in years) 7    
Weighted-average remaining contractual life for options exercisable (in years) 5    
Unrecognized compensation cost 3,143    
Compensation cost not yet recognized, weighted-average period for recognition (in years) 0.9    
2010 Plan [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized for future awards (in shares) 1,000,000    
Shares reserved for issuance (in shares) 554,998    
Performance Shares [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of new awards granted (in years) 3    
Weighted-Average Grant Date Fair Value [Abstract]      
Performance period for award (in years) 3    
Share-Based Liabilties [Member]
     
Weighted-Average Grant Date Fair Value [Abstract]      
Total share-based liabilities 2,530 664  
Amounts paid out related to share-based liability awards $ 506 $ 81 $ 22