Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Information [Abstract]
Capital Expenditures Incurred but Not yet Paid	$ 223,600	$ 282,800	$ 797,500	$ 507,000
Supplemental cash flow information:
Cash paid for interest	316,116	301,743	267,384
Cash paid for income taxes	2	30	53,457
Cash received for income tax refunds	174	61,403	7
Asset Retirement Obligation, Additions or Revisions	$ (10,063)	$ 22,472	$ 18,938