Unconsolidated Subsidiaries (Schedule) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Variable Interest Entity [Line Items]
Revenues	$ 31,440	$ 21,941	$ 96,321	$ 78,341
Gross profit	6,095	2,475	16,365	11,630
Variable interest entity, not primary beneficiary
Variable Interest Entity [Line Items]
Revenues	205,838	203,134	570,902	571,862
Gross profit	22,359	23,126	63,827	64,981
Income before income taxes	$ 17,408	$ 16,602	$ 48,986	$ 45,928

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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