Income Taxes (Summary of Components of the Net Deferred Tax Asset (Liability) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Deferred tax assets related to:
Unrealized hedge loss	$ 16,287
Accrued expenses	931
Capital loss carryforwards	1,800
Net operating loss carryforwards - Federal	8,078
Net operating loss carryforwards - State	858
IRC Section 43 credits	1,334
Total deferred tax assets	29,288
Valuation allowance on deferred tax assets	(12,657)
Deferred tax assets, net of valuation allowance	16,631
Deferred tax liabilities related to:
Properties and equipment	(16,515)
Incentive compensation	(116)
Total deferred tax liabilities	$ (16,631)