Segment Information, Reconciliation of Total Segment Profits to Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reconciliation [Abstract]
Net income	$ 9,305	$ 23,361	$ 29,788	$ 37,579
Net (income) loss attributable to non-controlling interest in subsidiaries	(47)	16	114	72
Net income attributable to controlling interest	9,258	23,377	29,902	37,651
Operating Segments
Segment Reconciliation [Abstract]
Net income	9,079	22,852	29,411	36,691
Intersegment Eliminations
Segment Reconciliation [Abstract]
Net income	$ 226	$ 509	$ 377	$ 888