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Restricted Unit Awards ("RUAs") - Additional Information (Details) - Restricted Unit Awards [Member] - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Compensation expense $ 1,800,000 $ 1,600,000 $ 833,000
Unrecognized compensation expense related to nonvested RUAs granted $ 902,000    
Remaining expense expected to be recognized over a weighted-average period 1 year 3 months 18 days    
Intrinsic value of nonvested RUAs $ 1,500,000    
Burlington [Member] | Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Approved grant of restricted units and other awards to employees 3,000,000    
RUAs granted with vesting range 3 years    
Burlington [Member] | Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
RUAs granted with vesting range 3 months