Segment Information, reconciliation of total segment profits to consolidated totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Revenues	$ 12,268	$ 14,589	$ 27,570	$ 25,292
Net income	11,658	14,490	26,574	24,036
Net loss attributable to non-controlling interest in subsidiaries	(147)	(7)	(335)	(6)
Net income attributable to controlling interest	11,805	14,497	26,909	24,042
Total segment profits [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Revenues	12,268	14,589	27,570	25,292
Elimination of intersegment profit [Member]
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Revenues	$ (610)	$ (99)	$ (996)	$ (1,256)