Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 213,969	$ 204,180
Cash paid for income taxes	0	27
Cash received for income tax refunds	174	59,117
Noncash Investing and Financing Items [Abstract]
Accrued capital expenditures	186,200	315,000	$ 282,800	$ 797,500
Increase (Decrease) in Asset Retirement Obligations	$ 1,645	$ 6,267