Derivative Financial Instruments (Details Textual)	3 Months Ended				3 Months Ended
	Mar. 31, 2013 USD ($) agreement	Apr. 01, 2012 USD ($)	Mar. 31, 2013 AUD	Dec. 31, 2012 USD ($)	Mar. 31, 2013 Fair Value Hedging Interest Rate Swap USD ($)	Apr. 01, 2012 Fair Value Hedging Interest Rate Swap USD ($)	Mar. 31, 2013 Minimum	Mar. 31, 2013 Maximum
Derivative Instruments, Gain (Loss) [Line Items]
Gains (loss) recongized and recorded in earnings related to fair value hedge					$ 800,000	$ 200,000
Interest Rate Swaps [Abstract]
Number of Interest Rate Swap Agreements	4
Notes bear interest at a rate	7.75%
Notional amount coincide with the terms of the non-recourse debt	100,000,000
Variable interest rate payment to the same counterparties							4.16%	4.29%
Fair value of the swap assets included as Other Non-Current Assests	5,500,000			6,200,000
Ineffective portion of Fair value interest rate swap	0
Fixed interest rate on cash flow interest rate derivative	9.70%
Interest Rate Swap Agreements			50,900,000
Net unrealized loss recognized in the periods and recorded in accumulated other comprehensive income, net of tax	100,000	0
Interest Rate Cash Flow Hedge Liability at Fair Value	(500,000)			(700,000)
Ineffective portion of Cash Flow Hedge interest rate swap	$ 0