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Stock Based Compensation Table of Stock Options Valuation Assumptions (Details) - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Common Stock - Class A      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividends declared per share $ 0.030 $ 0.025  
Employee Stock Option      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period 10 years    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 5 years    
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period 3 years    
Share-based Compensation Arrangement by Share-based Payment Award, Term Requirement Where Weighted Average Stock Price Must Exceed Book Value     20 days
Share-based Compensation Arrangement by Share-based Payment Award, Term Requirement Where Weighted Average Stock Price Plus Sum of Actual Cash Dividends Paid Must Exceed as Exchanged Book Value 20 days    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Historical Volatility 47.20%    
Risk-free Rate 2.44%    
Expected term (years) 6 years 6 months    
Employee Stock Option | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate 1.80%