Acquisitions, Divestitures, and Assets Held for Sale Assets Held for Sale (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Assets held for sale [Abstract]
Assets Held-for-sale Reasonably Certain Period for Sale	1
Disposal Group, Including Discontinued Operation, Assets, Current	$ 7,361,000	$ 7,361,000	$ 17,891,000
Asset Retirement Obligations Assets Held-for-sale Noncurrent	200,000	200,000
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	$ 66,000,000	$ 99,900,000