Fair Value Measurements (Schedule of Fair Value Measurements of Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current	$ 10,758	$ 3,302
Noncurrent	7,600	211
Total gross fair value	18,358	3,513
Less: counterparty set-off	1,208	3,513
Total net fair value	17,150
Current	1,208	10,026
Noncurrent		3,637
Total gross fair value	1,208	13,663
Less: counterparty set-off	1,208	3,513
Total net fair value		10,150
Parent Company [Member]
Current	10,758	3,302
Noncurrent	7,600	211
Current	1,208	10,026
Noncurrent		$ 3,637