Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net cash provided from operating activities included:
Income taxes (refunded from) paid to taxing authorities	$ (156)		$ (347)		$ 386
Interest paid	165,530		159,137		153,249
Non-cash investing and financing activities included:
Asset retirement costs capitalized, net	56,822	[1]	76,373	[1]	57,982	[1]
Increase (decrease) in accrued capital expenditures	$ 150,604		$ 27,079		$ (94,121)

[1] Includes cost incurred whether capitalized or expensed.