Consolidated Statements of Partners' Capital (USD $) In Thousands, unless otherwise specified	Total	General Partner [Member]	Common Unitholders [Member]	Subordinated Unitholder [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance at Dec. 31, 2011	$ 188,644	$ 3,515	$ 111,989	$ 72,238	$ 902
Partners' capital rollforward
Net income	16,331	326	9,500	6,505	0
Distributions	(24,732)	(495)	(14,451)	(9,786)	0
Equity compensation	1,905	0	1,905	0	0
Other comprehensive income (loss)	102	0	0	0	102
Ending balance at Dec. 31, 2012	182,250	3,346	108,943	68,957	1,004
Partners' capital rollforward
Net income	17,567	351	10,251	6,965	0
Distributions	(26,969)	(539)	(15,766)	(10,664)	0
Equity compensation	1,459	0	1,459	0	0
Other comprehensive income (loss)	(591)	0	0	0	(591)
Ending balance at Dec. 31, 2013	173,716	3,158	104,887	65,258	413
Partners' capital rollforward
Net income	11,258	510	7,319	3,429	0
Distributions	(36,687)	(732)	(27,579)	(8,376)	0
Conversion of subordinated units to common units	0	0	60,311	(60,311)	0
Proceeds from issuance of common units, net of issuance costs	395,794	0	395,794	0	0
Contribution of capital	8,405	8,405	0	0	0
Equity compensation	1,544	0	1,544	0	0
Other comprehensive income (loss)	(3,749)	0	0	0	(3,749)
Ending balance at Dec. 31, 2014	$ 550,281	$ 11,341	$ 542,276	$ 0	$ (3,336)