Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Capital Expenditures Incurred but Not yet Paid	$ 317,500	$ 302,800
Supplemental cash flow information:
Cash paid for interest	270,927	281,058	$ 316,116
Cash paid for income taxes	0	2	2
Cash received for income tax refunds	7,893	257	174
Asset Retirement Obligation, Additions or Revisions	$ 22,145	$ 14,685	$ (10,063)