Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Valuation Allowance [Line Items]
Benefit from income taxes	$ 343,865	$ 34,350	$ 351,332	$ 112,830
Benefit associated with asset impairment charges	794,000		794,000
Federal net operating losses and tax credits	426,400		426,400
State operating losses	$ 19,300		$ 19,300
Valuation Allowance, Operating Loss Carryforwards [Member] | Domestic Tax Authority [Member]
Valuation Allowance [Line Items]
Change in amount of valuation allowance				51,700
Valuation Allowance, Operating Loss Carryforwards [Member] | State and Local Jurisdiction [Member]
Valuation Allowance [Line Items]
Change in amount of valuation allowance				$ 6,300