Property, Plant and Equipment (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Minimum future lease payments under capital leases
2012	$ 18,322
2013	7,811
2014	2,223
2015	129
2016	115
2017 and thereafter	0
Total minimum payments due	28,601
Less: Amount representing interest	(1,590)
Present value of net minimum lease payments	27,010
Less: Current maturities	(17,119)
Non-current portion	9,891
Minimum future lease payments under operating leases
2012	5,099
2013	4,076
2014	3,963
2015	3,795
2016	682
2017 and thereafter	0
Total minimum payments due	$ 17,615