Operating Segments and Geographic Information (Reconciliation to Consolidated Statements of Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Operating income	$ 130,779	$ 83,852	$ 76,255
Equity income in unconsolidated joint ventures	4,898	4,146	2,890
Other income (expense), net	3,379	(1,788)	(8,492)
Interest expense, net	(6,131)	(3,930)	(4,480)
Income before income taxes	$ 132,925	$ 82,280	$ 66,173