Partnership Capital and Distributions - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	3 Months Ended				9 Months Ended	0 Months Ended	9 Months Ended
	Aug. 15, 2013	Apr. 02, 2013	Sep. 30, 2014	Dec. 31, 2012 Class B Units	Sep. 30, 2014 Maximum	Sep. 30, 2014 Cash Distributions for Limited and General Partner	Jun. 30, 2014 Cash Distributions for Limited and General Partner	Mar. 31, 2014 Cash Distributions for Limited and General Partner	Dec. 31, 2013 Cash Distributions for Limited and General Partner	Sep. 30, 2014 Cash Distributions for Limited and General Partner	Aug. 15, 2013 Subordinated units	Sep. 30, 2014 Class C Units
Limited Partners Capital Account [Line Items]
Cash distribution period										45 days
Cash distribution paid						$ 138,400,000				$ 390,500,000
Cash distribution per unit							$ 0.595	$ 0.575	$ 0.555
Cash distribution declaration date						Oct. 23, 2014
General partnership interest and distribution right		2.00%	2.00%
Maximum percentage of cash that can be distributed for general partner					50.00%
Subordinated units converted into common units	69,076,122
General partnership interest											one-for-one	one-for-one
Beneficial conversion feature				$ 58,300,000