Segment Information Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013 region	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Number of operating regions	11
Operating revenues	$ 401,388	$ 222,745	$ 1,177,337	$ 647,600
Income from operations	101,741	52,875	285,358	156,662
Depreciation and amortization	37,334	18,980	105,718	54,947
Interest expense	(16,029)	(8,814)	(53,352)	(26,052)
Interest income	992	928	2,985	2,759
Provision for income taxes	(22,240)	(15,303)	(22,534)	(46,051)
Expenditures for additions to property & equipment, net of grants from outside parties	40,231	57,343	146,557	145,600
North American & European Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	319,079	150,323	935,390	439,451
Income from operations	77,024	33,571	213,940	104,782
Depreciation and amortization	30,704	12,495	85,503	37,354
Interest expense	(12,473)	(4,621)	(41,566)	(14,107)
Interest income	926	783	2,730	2,407
Provision for income taxes	(17,296)	(10,764)	(6,634)	(33,723)
Expenditures for additions to property & equipment, net of grants from outside parties	31,277	24,023	105,203	50,761
Australian Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	82,309	72,422	241,947	208,149
Income from operations	24,717	19,304	71,418	51,880
Depreciation and amortization	6,630	6,485	20,215	17,593
Interest expense	(3,556)	(4,193)	(11,786)	(11,945)
Interest income	66	145	255	352
Provision for income taxes	(4,944)	(4,539)	(15,900)	(12,328)
Expenditures for additions to property & equipment, net of grants from outside parties	$ 8,954	$ 33,320	$ 41,354	$ 94,839