Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Information [Abstract]
Interest (1)	[1]	$ 136,733	$ 118,120
Income Taxes, Net of Refunds Received		98,157	(10,997)
Interest Costs Capitalized		14,000	17,000
Accrued Capital Expenditures		488,000	$ 371,000
Non-Cash Property Exchanges		$ 154,000

[1] Net of capitalized interest of $14 million and $17 million for the six months ended June 30, 2017 and 2016, respectively.