Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Net cash provided from operating activities included:
Income taxes paid to taxing authorities			$ 39
Interest paid	54,284		55,190
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	15,813	[1]	3,218	56,822	[1]
(Decrease) increase in accrued capital expenditures	$ (110,622)		$ 6,808

[1] Includes costs incurred whether capitalized or expensed.