Segment Information Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 region	Mar. 31, 2013
Segment Reporting Information [Line Items]
Number of operating regions	11
Operating revenues	$ 376,279	$ 374,950
Income from operations	74,875	76,200
Depreciation and amortization	37,641	34,223
Interest expense	13,641	20,120
Interest income	1,034	1,043
(Provision for)/benefit from income taxes	(22,900)	24,932
Expenditures for additions to property & equipment, net of grants from outside parties	58,818	35,060
North American & European Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	299,987	299,095
Income from operations	55,690	54,794
Depreciation and amortization	30,579	27,411
Interest expense	9,445	15,811
Interest income	902	888
(Provision for)/benefit from income taxes	(18,457)	30,049
Expenditures for additions to property & equipment, net of grants from outside parties	53,985	16,218
Australian Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	76,292	75,855
Income from operations	19,185	21,406
Depreciation and amortization	7,062	6,812
Interest expense	4,196	4,309
Interest income	132	155
(Provision for)/benefit from income taxes	(4,443)	(5,117)
Expenditures for additions to property & equipment, net of grants from outside parties	$ 4,833	$ 18,842