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Stock-Based Compensation Plans - Summary of Nonvested Stock Option Activity (Details) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Restricted Stock [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]    
Fully Vested Stock Based Compensation Issued To Retirement Eligible Employees 1,319,372 975,116
Nonvested Stock Option [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]    
Beginning Balance [1] 82,250  
Vested (82,250)  
Ending Balance [1] 0  
Nonvested, Weighted Average Exercise Price (in usd per share) [1] $ 0.00 $ 39.81
Vested, Weighted Average Exercise Price (in usd per share) $ 39.81  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number   279,000
[1] Excludes 279,000 of stock options issued to retirement-eligible employees as of December 31, 2015 as they are fully vested.