Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Interest, Net of Capitalized Interest	$ 252,030	$ 222,088	$ 197,383
Income Taxes, Net of Refunds Received	(39,293)	41,108	342,741
Accrued Capital Expenditures	388,000	$ 416,000	972,000
Non-cash investing and financing activities from property exchanges.			$ 5,000
Non-cash investing and financing activities from the Yates transaction	$ 3,834,000