Net Income per Limited Partnership Unit - Schedule of Reconciliation of Net Income and Allocation of Net Income to Limited Partners' Interest for Purposes of Computing Net Income per Limited Partner Unit (Parenthetical) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Quarterly dividend distributions paid (in dollars per unit)	$ 0.5225	$ 0.4775	$ 1.5475	$ 1.2248