Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Income tax expense (benefit)	$ 182,230	$ (46,947)	$ 183,045	$ (43,016)
Net operating loss carryforwards					$ 307,200
Period after REIT Conversion Assets Sold Subject to Income Taxes			10 years
Charitable contribution deduction carryforward [Member]
Tax Credit Carryforward [Line Items]
Tax carryforward					16,234
General business tax credit carryovers [Member]
Tax Credit Carryforward [Line Items]
Tax carryforward					36,779
Alternative Minimum Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Tax carryforward					$ 27,452