Organization, Description of Business and Basis of Presentation (Changes from New Accounting Pronouncements) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Item Effected [Line Items]
Distributions of earnings from investments in non-controlled entities	$ 51,754	$ 21,605
Net Cash Provided by (Used in) Operating Activities	277,902	266,883
Distributions in excess of earnings of non-controlled entities		0
Net Cash Provided by (Used in) Investing Activities	(160,233)	(182,658)
Property, Plant and Equipment, Gross	7,346,495			$ 7,235,468
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(1,732,486)			(1,682,633)
Property, Plant and Equipment, Net	5,614,009			5,552,835
Investments in non-controlled entities	1,126,773			1,082,511
Deferred revenue	119,258			117,795
Other noncurrent liabilities	34,764			30,350
Limited partner unitholders	2,271,486			2,267,231
Accounting Standards Update 2014-09 [Member]
Item Effected [Line Items]
Property, Plant and Equipment, Gross	7,346,495		$ 7,243,984
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(1,732,486)		(1,682,958)
Property, Plant and Equipment, Net	5,614,009		5,561,026
Investments in non-controlled entities	1,126,773		1,083,013
Deferred revenue	119,258		115,894
Other noncurrent liabilities	34,764		34,969
Limited partner unitholders	2,271,486		2,273,206
Scenario, Previously Reported [Member]
Item Effected [Line Items]
Distributions of earnings from investments in non-controlled entities		20,050
Net Cash Provided by (Used in) Operating Activities		265,328
Distributions in excess of earnings of non-controlled entities		1,555
Net Cash Provided by (Used in) Investing Activities		(181,103)
Restatement Adjustment [Member] | Accounting Standards Update 2016-15 [Member]
Item Effected [Line Items]
Distributions of earnings from investments in non-controlled entities		1,555
Net Cash Provided by (Used in) Operating Activities		1,555
Distributions in excess of earnings of non-controlled entities		(1,555)
Net Cash Provided by (Used in) Investing Activities		$ (1,555)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Item Effected [Line Items]
Property, Plant and Equipment, Gross	7,336,491			7,235,468
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(1,732,105)			(1,682,633)
Property, Plant and Equipment, Net	5,604,386			5,552,835
Investments in non-controlled entities	1,126,271			1,082,511
Deferred revenue	120,814			117,795
Other noncurrent liabilities	29,415			30,350
Limited partner unitholders	2,265,511			$ 2,267,231
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Item Effected [Line Items]
Property, Plant and Equipment, Gross	10,004		8,516
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(381)		(325)
Property, Plant and Equipment, Net	9,623		8,191
Investments in non-controlled entities	502		502
Deferred revenue	(1,556)		(1,901)
Other noncurrent liabilities	5,349		4,619
Limited partner unitholders	$ 5,975		$ 5,975