Earnings per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015	Sep. 30, 2014		Dec. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 16,493	$ 16,250		$ 47,731	$ 49,634
Net income attributable to General Partner	0	3,985	[1]	0	15,461	[1]
Net Income (Loss) Allocated to Limited Partners	16,493	12,265		47,731	34,173
Incentive Distribution, Distribution	(326)	0		(481)	0		$ 0
Distribution Made to Limited Partner, Cash Distributions Declared				(49,405)
Net income attributable to Predecessor	0	3,985		0	15,461
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	(925)	(1,763)		(1,674)	(4,409)
Increase (Decrease) in Partners' Capital	326	3,985		481	15,461
Common Units [Member]
Earnings Per Share [Abstract]
Distribution Made to Limited Partner, Cash Distributions Declared	(8,766)	(7,014)		(25,086)	(19,291)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	(474)	(882)		(858)	(2,205)
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	$ 8,292	$ 6,132		$ 24,228	$ 17,086
Weighted Average Number of Shares Outstanding, Basic	24,017,000	22,811,000		24,006,000	22,811,000
Weighted Average Number of Shares Outstanding, Diluted	24,024,000	22,883,000		24,024,000	22,853,000
Earnings Per Share, Basic	$ 0.35	$ 0.27		$ 1.01	$ 0.75
Earnings Per Share, Diluted	$ 0.35	$ 0.27		$ 1.01	$ 0.75
Subordinated Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment				0
Earnings Per Share [Abstract]
Distribution Made to Limited Partner, Cash Distributions Declared	$ (8,326)	$ (7,014)		$ (23,838)	$ (19,291)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	(451)	(881)		(816)	(2,204)
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	$ 7,875	$ 6,133		$ 23,022	$ 17,087
Weighted Average Number of Shares Outstanding, Basic and Diluted	22,811,000	22,811,000		22,811,000	22,811,000
Earnings Per Share, Basic and Diluted	$ 0.35	$ 0.27		$ 1.01	$ 0.75

[1] For historical periods prior to the Wholesale Acquisition, we have applied the two-class method to calculate earnings per unit. The net income of WRW prior to the Wholesale Acquisition was allocated entirely to the General Partner.