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Stock-Based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares available for issuance under plans (in shares) 1,653,855    
Weighted average fair value of stock options granted (in dollars per share)   $ 20.30 $ 16.89
Options granted (in shares) 0 35,800 89,575
Weighted average forfeiture rate 7.40%    
Net proceeds from exercise of stock options $ 1,266 $ 1,444 $ 1,542
Average expected term   5 years 5 years
Risk-free interest rate (as a percent)   1.30% 1.50%
Expected volatility (as a percent)   37.00% 38.00%
Dividend yield (as a percent)   3.60% 3.60%
Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Expiration period, minimum 10 years    
Compensation expense recorded during the period in general and administrative expense $ 649 $ 729 $ 510
Net proceeds from exercise of stock options 1,265 1,444 1,542
Unrecognized compensation expense $ 869    
Weighted-average period for recognition of unrecognized compensation expense 1 year 6 months 22 days    
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Weighted average forfeiture rate 10.10%    
Compensation expense recorded during the period in general and administrative expense $ 8,072 $ 7,316 $ 5,545
Unrecognized compensation expense $ 12,913    
Weighted-average period for recognition of unrecognized compensation expense 2 years 1 month 21 days    
Performance-based Stock Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Compensation expense recorded during the period in general and administrative expense $ 840    
Unrecognized compensation expense $ 1,681    
Weighted-average period for recognition of unrecognized compensation expense 2 years    
Share-based Compensation Arrangement By Share-based Payment Award, Component Weight, Percentage 50.00%    
Minimum shares issued for each PSU (in shares) 0    
Maximum shares issued for each PSU (in shares) 2    
Average expected term 2 years 9 months 18 days    
Risk-free interest rate (as a percent) 1.60%    
Expected volatility (as a percent) 21.40%    
Dividend yield (as a percent) 0.00%    
Intrinsic value of unvested PSUs $ 2,630