Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended			12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015	Dec. 31, 2015	[1]
Net cash provided from operating activities included:
Income taxes (refunded) paid to taxing authorities	$ (101)		$ 100
Interest paid	134,583		128,132
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	4,655	[1]	19,862	$ 22,184
Increase (decrease) in accrued capital expenditures	$ 12,523		$ (195,472)

[1] Includes costs incurred whether capitalized or expensed.