Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended			12 Months Ended
	Sep. 30, 2019		Sep. 30, 2018	Dec. 31, 2018	[1]
Net cash provided from operating activities included:
Income taxes refunded from taxing authorities			$ 7,521
Interest paid	$ (151,602)		(161,444)
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	812	[1]	20,452	$ 28,826
Decrease in accrued capital expenditures	$ (4,424)		$ (107,070)

[1] Includes costs incurred whether capitalized or expensed.