Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended			12 Months Ended
	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014	[1]
Net cash provided from operating activities included:
Income taxes paid to taxing authorities	$ 100		$ 41
Interest paid	128,132		144,596
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	19,862	[1]	7,815	$ 56,822
(Decrease) increase in accrued capital expenditures	$ (195,472)		$ 41,707

[1] Includes costs incurred whether capitalized or expensed.