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Unit-Based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Restricted Stock Units (RSUs) [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Aggregate value of units issued $ 1.1 $ 1.3 $ 1.5      
Restricted unit-based compensation granted to Partnership's employee 32,054 31,961 36,878      
Restricted units expense       $ 1.2 $ 1.0 $ 1.0
Restricted units, vesting period       3 years    
Share-based Compensation Arrangement by Share-based Payment Award, Description       Each restricted unit is equal in value to one of the Partnership's common units plus reinvested distributions from the grant date to the vesting date.    
Non-management directors [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common units granted 10,447       9,521 7,362
Aggregate value of units issued $ 0.4