Interim Financial Information Interim Financial Information (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total assets	$ 4,500,800	$ 4,396,716
Assets, Current	2,201,957	2,188,370
Liabilities, Current	2,111,874	2,039,268
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets	26,210	23,871
Assets, Current	12,721	12,849
Long-Lived Assets	13,489	11,022
Total liabilities	30,718	25,321
Liabilities, Current	9,783	8,257
Liabilities, Noncurrent	$ 20,935	$ 17,064