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Share-Based Compensation - Summary of Assumptions (Details) - 2007 Long-Term Incentive Plan
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Director and Officers [Member]      
Expected dividend yield 22.00% 18.00%  
Expected volatility 41.19% 44.14%  
Risk-free interest rate 2.00% 1.97%  
Expected life (in years) 7 years 8 months 5 days 8 years  
Employees      
Expected dividend yield 25.00% 22.00% 14.00%
Expected volatility 34.50% 42.71% 44.85%
Risk-free interest rate 1.73% 1.41% 2.26%
Expected life (in years) 5 years 8 months 8 days 8 years 8 years