Net Income Per Limited Partner Unit (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allocation of net income to determine net income available to limited partners:
Distributions, excluding general partner's IDRs	$ 16,853	$ 12,486
General partner’s IDRs	410
DERs	3	1
Distributions and DERs declared	17,266	12,487
Undistributed earnings	4,855
Net income available to limited partners – basic and diluted	22,121
Excess distribution over earnings		(2,005)
Net income available to limited partners – basic		10,482
Net income per limited partner unit – basic and diluted:
Net income per limited partner unit basic and diluted	$ 0.37	$ 0.18
Net income per limited partner unit – basic:
Weighted-average units outstanding	29,426	28,790
Net income per limited partner unit – diluted:
Weighted-average units outstanding	29,426	28,790
Weighted-average units outstanding – diluted	29,426	28,792
General Partner Valero [Member]
Allocation of net income to determine net income available to limited partners:
Distributions, excluding general partner's IDRs	345	250
General partner’s IDRs	410
DERs	0	0
Distributions and DERs declared	755	250
Undistributed earnings	97
Net income available to limited partners – basic and diluted	852
Excess distribution over earnings		(40)
Net income available to limited partners – basic		210
Limited Partner, Common Units [Member]
Allocation of net income to determine net income available to limited partners:
Distributions, excluding general partner's IDRs	8,519	6,118
General partner’s IDRs	0
DERs	0	0
Distributions and DERs declared	8,519	6,118
Undistributed earnings	2,404
Net income available to limited partners – basic and diluted	10,923
Excess distribution over earnings		(982)
Net income available to limited partners – basic		5,136
Add: DERs		1
Net income available to limited partners - diluted		5,137
Net income per limited partner unit – basic and diluted:
Weighted-average units outstanding	29,426
Net income per limited partner unit basic and diluted	$ 0.37
Net income per limited partner unit – basic:
Weighted-average units outstanding		28,790
Net income per limited partner unit – basic		$ 0.18
Net income per limited partner unit – diluted:
Weighted-average units outstanding		28,790
Common equivalent units for nonvested restricted units		2
Weighted-average units outstanding – diluted		28,792
Net income per limited partner unit – diluted		$ 0.18
Distribution Equivalent Rights [Member]
Allocation of net income to determine net income available to limited partners:
Distributions, excluding general partner's IDRs	0	0
General partner’s IDRs	0
DERs	3	1
Distributions and DERs declared	3	1
Undistributed earnings	1
Net income available to limited partners – basic and diluted	4
Excess distribution over earnings		(1)
Net income available to limited partners – basic		0
Subordinated Unitholder Valero [Member]
Allocation of net income to determine net income available to limited partners:
Distributions, excluding general partner's IDRs	7,989	6,118
General partner’s IDRs	0
DERs	0	0
Distributions and DERs declared	7,989	6,118
Undistributed earnings	2,353
Net income available to limited partners – basic and diluted	10,342
Excess distribution over earnings		(982)
Net income available to limited partners – basic		5,136
Add: DERs		0
Net income available to limited partners - diluted		$ 5,136
Net income per limited partner unit – basic and diluted:
Weighted-average units outstanding	28,790
Net income per limited partner unit basic and diluted	$ 0.36
Net income per limited partner unit – basic:
Weighted-average units outstanding		28,790
Net income per limited partner unit – basic		$ 0.18
Net income per limited partner unit – diluted:
Weighted-average units outstanding		28,790
Common equivalent units for nonvested restricted units		0
Weighted-average units outstanding – diluted		28,790
Net income per limited partner unit – diluted		$ 0.18