Leases (Schedule of Maturity of Lease Liabilities) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating Leases, 2019	$ 164,979	[1]
Operating Leases, 2020	109,790	[1]
Operating Leases, 2021	58,415	[1]
Operating Leases, 2022	53,639	[1]
Operating Leases, 2023	53,140	[1]
Operating Leases, Remaining	465,611	[1]
Operating Leases, Total future minimum payments	905,574	[1]
Finance Leases, 2019	801
Finance Leases, 2020	1,069
Finance Leases, 2021	1,069
Finance Leases, 2022	1,069
Finance Leases, 2023	1,069
Finance Leases, Remaining	5,610
Finance Leases, Total future minimum payments	10,687
Total Leases, 2019	165,780
Total Leases, 2020	110,859
Total Leases, 2021	59,484
Total Leases, 2022	54,708
Total Leases, 2023	54,209
Total Leases, Remaining	471,221
Total Leases, Future minimum payments	916,261
Minimum lease payments for leases signed but not yet commenced	$ 272,200
Lease duration for leases signed but not yet commenced	20 years

[1] Excludes $272.2 million of minimum lease payments for leases entered but not yet commenced. These payments relate to an expansion of an existing gas processing plant and payments are anticipated to commence at the end of 2019 for 20 years.