Segment Reporting (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Reconciliation of segment operating income to Consolidated
Operating income segment totals	$ 44,692	$ 38,913	$ 139,524	$ 119,948
Unallocated corporate expenses	(10,801)	(5,510)	(35,412)	(22,616)
Total operating income	33,891	33,403	104,112	97,332
Interest expense, net	(2,684)	(2,256)	(7,374)	(6,513)
Loss from equity in joint ventures	(1,376)	(890)	(3,817)	(2,660)
Other, net	404	(2,028)	1,552	(1,463)
Consolidated income before income taxes	$ 30,235	$ 28,229	$ 94,473	$ 86,696