Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017
Supplemental Cash Flow Information [Abstract]
Interest (1)	[1]	$ 172,076	$ 202,320
Income Taxes, Net of Refunds Received		81,059	92,391
Interest Costs Capitalized		18,000	21,000
Accrued Capital Expenditures		702,000	545,000
Non-Cash Property Exchanges		222,000	$ 214,000
Non-Cash Other Property, Plant and Equipment		$ 49,000

[1] Net of capitalized interest of $18 million and $21 million for the nine months ended September 30, 2018 and 2017, respectively.