General (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Carrying amounts and classification of assets and liabilities
Current assets	$ 828,335	$ 973,364
TOTAL ASSETS	1,248,305	1,304,794
Current liabilities	226,032	307,310
Total liabilities	305,079	358,960
Variable Interest Entity, Primary Beneficiary [Member]
Carrying amounts and classification of assets and liabilities
Current assets	5,128	6,058
Noncurrent assets	134,131	107,723
TOTAL ASSETS	139,259	113,781
Current liabilities	60,986	36,364
Noncurrent liabilities	18,193	17,359
Total liabilities	$ 79,179	$ 53,723