Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Net cash provided from operating activities included:
Income taxes paid to (refunded from) taxing authorities	$ 98	$ (101)
Interest paid	136,863	134,583
Non-cash investing and financing activities included:
Increase in asset retirement costs capitalized	6,460	4,655
Increase in accrued capital expenditures	$ 52,289	$ 12,523