Annual report pursuant to Section 13 and 15(d)

Employee Retirement Benefits (Narrative) (Details)

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Employee Retirement Benefits (Narrative) (Details)
12 Months Ended
Dec. 31, 2015
USD ($)
employee
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Defined Benefit Plan Disclosure [Line Items]      
Maximum matching percentage by employer 6.00%    
Contributions to the plan $ 591,000 $ 528,000 $ 457,000
Expected contributions in 2016 70,000    
Settlement contribution amount $ 650,000    
Percentage of settlement contributed 95.00%    
Pension settlement costs $ 1,222,276    
Number of active employees covered by U.K. based subsidiary Austin Taylor | employee 2    
Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Investments used to fund the plan $ 2,623,000 $ 3,756,000