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Employee Benefit Plans Money Market Pension Plan (MPPP) (Details) - Money Purchase Pension Plan [Member]
$ in Thousands
12 Months Ended
Dec. 31, 2015
USD ($)
year
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Defined Benefit Plan Disclosure [Line Items]      
Minimum qualifying age under plan | year 21    
Service period 1 year    
Minimum number of hours for allocation of an employer contribution 1000 hours    
Employer contribution 6.75%    
Additional contribution by employer 2.75%    
Matching contributions vesting period 5 years    
Expense attributable to the plan | $ $ 926 $ 898 $ 1,000