Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	6 Months Ended			12 Months Ended
	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015	[1]
Net cash provided from operating activities included:
Income taxes refunded from taxing authorities	$ (101)		$ 0
Interest paid	69,991		73,189
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	3,740	[1]	18,684	$ 22,184
Decrease in accrued capital expenditures	$ (4,741)		$ (156,897)

[1] Includes costs incurred whether capitalized or expensed.