Segment Information, Reconciliation of Total Segment Profits to Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	$ 17,678	$ 14,917
Net loss attributable to non-controlling interest in subsidiaries	(65)	(188)
Net income attributable to controlling interest	17,743	15,105
Reportable Segments [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	16,983	15,303
Intersegment Eliminations [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Net income	$ 695	$ (386)