Segment Information, Reconciliation of Total Segment Profits to Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	$ 18,141	$ 11,658	$ 35,819	$ 26,574
Net loss attributable to non-controlling interest in subsidiaries	(51)	(147)	(116)	(335)
Net income attributable to controlling interest	18,192	11,805	35,935	26,909
Reportable Segments [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	18,334	12,268	35,317	27,570
Intersegment Eliminations [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	$ (193)	$ (610)	$ 502	$ (996)