CONSOLIDATED STATEMENTS OF CASH FLOWS Parenthetical - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Significant Noncash Transactions [Line Items]
Capital Expenditures Incurred but Not yet Paid - Instant			$ 97,355	$ 357,156
Accounts Payable and Accrued Liabilities [Member]
Other Significant Noncash Transactions [Line Items]
Capital Expenditures Incurred but Not yet Paid - Instant			$ 97,400	$ 357,200	$ 217,800
Rocky Mountain Acquisition 2014 [Member]
Other Significant Noncash Transactions [Line Items]
Noncash or Part Noncash Acquisition, Net Nonmonetary Assets Acquired (Liabilities Assumed)	$ 6,200
Rocky Mountain Non-Cash Asset Trade 2013 [Member]
Other Significant Noncash Transactions [Line Items]
Noncash or Part Noncash Acquisition, Net Nonmonetary Assets Acquired (Liabilities Assumed)		$ 25,000