Unconsolidated Subsidiaries (Schedule) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Variable Interest Entity [Line Items]
Revenues	$ 181,076	$ 178,007	$ 349,658	$ 351,428
Gross profit	43,428	40,529	82,563	80,534
Net income	6,788	3,116	11,766	5,918
Variable interest entity, not primary beneficiary
Variable Interest Entity [Line Items]
Revenues	174,554	160,281	368,728	305,351
Gross profit	19,857	19,673	41,854	38,421
Income before income taxes	13,616	13,246	29,326	26,367
Net income	$ 10,110	$ 9,717	$ 21,791	$ 19,727