Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Interest (1)	[1]	$ 202,320	$ 184,476
Income Taxes, Net of Refunds Received		92,391	(2,094)
Interest Costs Capitalized		21,000	25,000
Accrued Capital Expenditures		545,000	$ 375,000
Non-Cash Property Exchanges		$ 214,000

[1] Net of capitalized interest of $21 million and $25 million for the nine months ended September 30, 2017 and 2016, respectively.