Related Party Transactions (Unaudited Financial Information from Significant Equity Investees) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transactions [Abstract]
Revenues	$ 1,504,141	$ 1,341,123	$ 4,244,385	$ 3,797,546
Gross profit	49,497	42,973	147,013	111,468
Income (loss) from continuing operations	12,126	3,265	36,955	7,950
Net income (loss)	11,678	3,121	35,240	6,583
Net income (loss) attributable to Companies	$ 11,678	$ 3,300	$ 35,240	$ 7,486