Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Narratives) (Details)

v2.4.0.6
Stockholders' Equity (Narratives) (Details) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 3,700,000    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used The fair value of restricted stock awards is determined based on the number of shares granted and the quoted price of our common stock. We use a Black-Scholes-Merton option pricing model to estimate the fair value of stock options issued. The Black-Scholes-Merton option pricing model incorporates various and highly subjective assumptions, including expected term and expected volatility. We have reviewed our historical pattern of option exercises and have determined that meaningful differences in option exercise activity existed among employee job categories. Therefore, we have categorized these awards into two groups of employees for valuation purposes.    
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value     $ 2.84
Options granted 0 0  
Share Based Compensation Arrangement By Share Based Payment Award Options Vested In Period Fair Value $ 560,000 $ 379,000 $ 377,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value 1,300,000 287,000 511,000
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options 2,100,000 947,000 659,000
Defined Contribution Plan Maximum Annual Contribution Per Employee Amount 17,000 16,500 16,500
Defined Contribution Plan Maximum Annual Catchup Contribution Per Employee Amount 5,500    
Defined Contribution Plan Employer Matching Contribution Percent 10.00%    
Defined Contribution Plan Employer Discretionary Contribution Amount 7,500,000 7,100,000 6,900,000
Common Stock - Class A [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock Repurchased During Period, Shares 1,500,000 5,200,000 8,000,000
Stock Repurchased During Period, Value 14,000,000 52,600,000 80,800,000
Total shares retired in the current year 1,800,000 5,200,000 8,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 15,700,000    
Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized share-based compensation expense 111,000    
Unvested stock options 43,000    
Weighted average period for recognition of unvested shares 1 year 4 months 24 days    
Restricted Stock [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized share-based compensation expense $ 6,400,000    
Unvested restricted stock awards 1,100,000    
Weighted average period for recognition of unvested shares 2 years 2 months 12 days