Segment Information Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Number of Operating Regions	11
Operating revenues	$ 400,741	$ 217,419	$ 775,949	$ 424,855
INCOME FROM OPERATIONS	107,417	62,473	183,617	103,787
Depreciation and amortization	34,161	18,334	68,384	35,967
Interest expense	(17,203)	(8,622)	(37,323)	(17,238)
Interest income	950	964	1,993	1,831
Benefit from/(provision for) income taxes	(25,226)	(18,443)	(294)	(30,748)
Expenditures for additions to property & equipment, net of grants from outside parties	72,773	46,376	106,326	88,257
Australian Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	83,525	72,364	159,638	135,727
INCOME FROM OPERATIONS	25,295	22,575	46,701	32,576
Depreciation and amortization	6,773	5,793	13,585	11,108
Interest expense	(3,921)	(3,901)	(8,230)	(7,752)
Interest income	35	145	189	207
Benefit from/(provision for) income taxes	(5,839)	(6,023)	(10,956)	(7,789)
Expenditures for additions to property & equipment, net of grants from outside parties	13,558	32,442	32,400	61,519
North American & European Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	317,216	145,055	616,311	289,128
INCOME FROM OPERATIONS	82,122	39,898	136,916	71,211
Depreciation and amortization	27,388	12,541	54,799	24,859
Interest expense	(13,282)	(4,721)	(29,093)	(9,486)
Interest income	915	819	1,804	1,624
Benefit from/(provision for) income taxes	(19,387)	(12,420)	10,662	(22,959)
Expenditures for additions to property & equipment, net of grants from outside parties	$ 59,215	$ 13,934	$ 73,926	$ 26,738