Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts	$ 3,114	$ 3,019
Accumulated depreciation	343,535	319,769
Accumulated amortization	32,308	29,515
Accounts Payable	215,751	273,666
Due to Related Parties	3,407	5,033
Accrued Liabilities	85,688	85,047
Other Liabilities, Current	$ 11,880	$ 13,281
Common stock, $0.01 par value	$ 0.01	$ 0.01
Common stock shares authorized	100,000	100,000
Common stock shares issued	45,104	44,863
Treasury stock shares	972	931
Variable Interest Entity, Primary Beneficiary [Member]
Accounts Payable	$ 193,885	$ 243,548
Due to Related Parties	3,402	5,033
Accrued Liabilities	20,243	22,240
Other Liabilities, Current	$ 3,436	$ 4,246