Employee Benefit 401(k) Plans And Deferred Retirement Compensation Agreements (Details) - USD ($)
 12 Months Ended
Jun. 30, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Minimum employee subscription rate, percentage of compensation   1.00%    
Maximum employee subscription rate, percentage of compensation   60.00%    
Employee pre-tax contributions vested percentage   100.00%    
Vesting rate   20.00%    
Percentage vested after total service period   100.00%    
Employees' vesting rights   Participants are always 100 percent vested in their pre-tax contributions and will begin vesting in any matching or profit sharing contributions made on their behalf after two years of service with the Company at a rate of 20 percent per year, becoming 100 percent vested after a total of six years of service with the Company.    
Expenses for employee benefit plan   $ 1,029,000 $ 970,000 $ 0
Minimum [Member]        
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Employer contribution vesting period   2 years    
Maximum [Member]        
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Employer contribution vesting period   6 years    
Messr Lefkowitz And Messr Thomas [Member]        
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Expenses for employee benefit plan       1,200,000
Messr Hersh [Member]        
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Expenses for employee benefit plan $ 2,300,000      
Deferred Retirement Compensation Units [Member]        
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]        
Expenses for employee benefit plan   $ 0 $ 0 $ 2,957,000