Business Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of segment profit to income before income taxes
Segment profit	$ 62,166	$ 59,248	$ 183,710	$ 203,529
Stock compensation expense	(11,961)	(4,524)	(25,983)	(14,764)
Non-controlling interest segment profit (loss)	(1,323)		(3,301)
Depreciation and amortization	(23,956)	(17,654)	(66,665)	(50,770)
Interest expense	(2,879)	(789)	(5,719)	(2,191)
Interest income	241	291	827	1,002
Income before income taxes	$ 22,288	$ 36,572	$ 82,869	$ 136,806