Unconsolidated Subsidiaries (Schedule) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Variable Interest Entity [Line Items]
Revenues	$ 21,941	$ 32,402	$ 78,341	$ 85,778
Gross profit	2,475	1,647	11,630	9,852
Variable interest entity, not primary beneficiary
Variable Interest Entity [Line Items]
Revenues	203,134	178,009	571,862	483,360
Gross profit	23,126	21,367	64,981	59,788
Income before income taxes	$ 16,602	$ 14,755	$ 45,928	$ 41,122