Derivative Financial Instruments - Australia Ravenhall (Details)	3 Months Ended		9 Months Ended			12 Months Ended		3 Months Ended	9 Months Ended						9 Months Ended
	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2014 Ravenhall, Australia USD ($)	Dec. 31, 2013 Ravenhall, Australia USD ($)	Sep. 30, 2014 Ravenhall, Australia Interest Rate Swap USD ($)	Sep. 30, 2014 Ravenhall, Australia Interest Rate Cap USD ($)	Sep. 30, 2014 Ravenhall, Australia Interest Rate Cap USD ($)	Sep. 30, 2014 Ravenhall, Australia Other Noncurrent Liabilities USD ($)	Sep. 30, 2014 Ravenhall, Australia Other Noncurrent Assets Interest Rate Cap USD ($)	Sep. 30, 2014 Ravenhall, Australia Design and construction phase Interest Rate Swap USD ($)	Sep. 30, 2014 Ravenhall, Australia Design and construction phase Interest Rate Swap AUD	Sep. 30, 2014 Ravenhall, Australia Operating phase Interest Rate Swap AUD	Sep. 30, 2014 Ravenhall, Australia Cash Flow Hedge USD ($)
Derivative [Line Items]
Fixed interest rate on derivative												3.34%	3.34%	4.21%
Notional amount coincide with the terms of the non-recourse debt							$ 424,000,000					$ 74,000,000	85,000,000	486,000,000
Unrealized losses, net of tax, related to cash flow hedge	(4,877,000)	(3,000)	(4,858,000)	138,000											(4,900,000)
Fair value of the swap liability										(7,000,000)
Ineffective portion of Cash Flow Hedge interest rate swap					0	0
Payments on non-recourse debt			4,511,000	27,153,000					1,700,000
Loss related to decline in derivative fair value								500,000
Interest rate swap asset value											$ 1,200,000