Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental cash flow information:
Cash paid for interest	$ 209,815	$ 102,043	$ 70,088
Cash paid for income taxes	29,017	829	16,030
Cash received for income tax refunds	(174)	(13,866)	(116)
Non-cash investing activities:
Increase in accrued capital expenditures	89,482	49,039	173,591
Acquisition of assets through issuance of common stock (Note 14)	0	176,563	0
Asset retirement obligation additions and revisions, net	$ 8,835	$ 3,808	$ 5,506