Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended			12 Months Ended
	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2019	[1]
Net cash provided from operating activities included:
Income taxes refunded from taxing authorities	$ 343		$ 0
Interest paid	(145,319)		(151,602)
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	4,587	[1]	812	$ 11,193
Decrease in accrued capital expenditures	$ (38,942)		$ (4,424)

[1] Includes costs incurred whether capitalized or expensed.