Acquisitions (Schedule of Pro Forma Consolidated Results of Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenues:
As reported	$ 305,353	$ 484,809
Net income from continuing operations attributable to limited partners:
As reported	12,031	12,103
Net loss from discontinued operations attributable to limited partners:
As reported	912	(576)
Net income from continuing operations per unit attributable to limited partners - basic:
As reported	$ 0.34	$ 0.45
Net loss from discontinued operations per unit attributable to limited partners - basic:
As reported	$ 0.03	$ (0.02)
Net income from continuing operations per unit attributable to limited partners - diluted:
As reported	$ 0.34	$ 0.45
Net loss from discontinued operations per unit attributable to limited partners - diluted:
As reported	$ 0.03	$ (0.02)
Limited Partner [Member] | Cardinal and West Texas Pipeline Limited Partnership [Member]
Revenues:
As reported		484,809
Pro forma		503,238
Net income from continuing operations attributable to limited partners:
As reported		12,103
Pro forma		2,882
Net loss from discontinued operations attributable to limited partners:
As reported		(576)
Pro forma		$ (576)
Net income from continuing operations per unit attributable to limited partners - basic:
As reported		$ 0.45
Pro forma		$ 0.11
Net loss from discontinued operations per unit attributable to limited partners - basic:
As reported		$ (0.02)
Pro forma		$ (0.02)
Net income from continuing operations per unit attributable to limited partners - diluted:
As reported		$ 0.45
Pro forma		$ 0.11
Net loss from discontinued operations per unit attributable to limited partners - diluted:
As reported		$ (0.02)
Pro forma		$ (0.02)