Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, expensed	$ 146,560	$ 185,140	$ 117,442
Cash paid for interest, capitalized	32,146	24,202	79,253
Cash paid for income taxes	6,340	5,033	28,895
Cash received from income tax refunds	(50,163)	(13,193)	(17,087)
Noncash investing and financing activities
Increase in asset retirement obligations	14,866	6,500	26,946
Increase (decrease) in liabilities for capital expenditures	(97,278)	215	(18,321)
Decrease in restricted cash	0	0	1,050,328	[1]
Other Significant Noncash Transactions [Line Items]
Retirement of treasury stock	0	$ 0	$ 0
Treasury Stock [Member]
Other Significant Noncash Transactions [Line Items]
Retirement of treasury stock	$ 884,129

[1] (1)During 2013, proceeds from the sales of our oil and natural gas property dispositions in 2012, which were held by a qualified intermediary, were released primarily to fund a portion of the CCA acquisition.