Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans (Details Textual)

v2.4.0.6
Employee Benefit Plans (Details Textual) (USD $)
 12 Months Ended 6 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2012
Plan
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Plans in Red Zone [Member]
Dec. 31, 2012
Plans in Yellow Zone [Member]
Dec. 31, 2012
Plans in Green Zone [Member]
Dec. 31, 2012
Selling, General and Administrative Expenses [Member]
Dec. 31, 2011
Selling, General and Administrative Expenses [Member]
Dec. 31, 2010
Selling, General and Administrative Expenses [Member]
Dec. 31, 2012
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Members
Jun. 30, 2009
2004 Stock Incentive Plan [Member]
Common Class A [Member]
Dec. 31, 2012
2004 Stock Incentive Plan [Member]
Common Class A [Member]
Executive Officer [Member]
Dec. 31, 2012
2012 Plan [Member]
Dec. 31, 2012
2012 Formula Plan [Member]
Dec. 31, 2012
2012 Formula Plan [Member]
Common Class A [Member]
Board Of Directors Chairman [Member]
Dec. 31, 2012
2005 Formula Restricted Stock Plan for Non-Employee Directors [Member]
Dec. 31, 2012
2004 Plan and 2012 Plan [Member]
Common Class A [Member]
Maximum [Member]
Dec. 31, 2012
2004 Plan and 2012 Plan [Member]
Common Class A [Member]
Minimum [Member]
Dec. 31, 2012
401(k) plan [Member]
Dec. 31, 2011
401(k) plan [Member]
Dec. 31, 2010
401(k) plan [Member]
Dec. 31, 2012
Stock Options [Member]
2004 Plan and 2012 Plan [Member]
Common Class A [Member]
Dec. 31, 2012
Restricted Stock [Member]
2004 Stock Incentive Plan [Member]
Dec. 31, 2012
Restricted Stock [Member]
2012 Plan [Member]
Dec. 31, 2012
Non-vested restricted stock [Member]
Dec. 31, 2012
Non-vested restricted stock [Member]
Restricted Stock Units R S U [Member]
Dec. 31, 2011
Non-vested restricted stock [Member]
Restricted Stock Units R S U [Member]
Dec. 31, 2010
Non-vested restricted stock [Member]
Restricted Stock Units R S U [Member]
Dec. 31, 2012
Non-vested restricted stock [Member]
Restricted Stock Units R S U [Member]
Selling, General and Administrative Expenses [Member]
Dec. 31, 2011
Non-vested restricted stock [Member]
Restricted Stock Units R S U [Member]
Selling, General and Administrative Expenses [Member]
Employee Benefit Plans (Textual) [Abstract]                                                            
Employer contribution                                     $ 4,400,000 $ 1,600,000 $ 500,000                  
Number of shares authorized                     5,000,000   2,000,000 300,000                                
Number of shares issuable                               0                            
Restricted stock vesting period                                 3 years 6 months         3 years 3 years            
Stock option expiration period                                           10 years                
Restricted stock shares                       426,000     25,000                              
Stock option compensation expense             100,000 400,000 500,000                                     2,300,000 5,000,000 3,300,000
Tax benefits recognized related to the compensation expenses 100,000 200,000 200,000                                             1,900,000 1,200,000 900,000    
Total compensation cost related to non-vested options not yet recognized                                                 8,400,000          
Multi-Employer Benefit AI Pension Plan       Less than 65 percent Between 65 and less than 80 percent At least 80 percent                                                
Total compensation cost related to non-vested options expected to be recognized over weighted average period 3 years                                               1 year 10 months 24 days          
Members of senior management                   0                                        
Employee Benefit Plans (Additional Textual) [Abstract]                                                            
Number of active stock compensation plans 3                                                          
Additional terminated plans with outstanding grants 2                                                          
Deferred compensation plan vested 0.33                                                          
Number of employee to make contribution under multi-employer plan $ 200                                                          
Pension Protection 2006                                                          
Number of employee increase / (decrease) under multi employer benefit percentage 5.10% 4.10%                                                        
Total contributions of multi employer Plan   5.00% 5.00%