Segment Information Segments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) reportable_segment region	Sep. 30, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of operating regions | region			11
Number of reportable segments | reportable_segment			3
Operating revenues	$ 546,299,000	$ 432,543,000	$ 1,485,548,000	$ 1,223,385,000
Income/(loss) from operations	117,559,000	123,116,000	289,630,000	308,100,000
Depreciation and amortization	48,303,000	40,277,000	138,568,000	116,130,000
Interest expense, net	17,239,000	12,572,000	48,369,000	42,752,000
Loss on settlement of foreign currency forward purchase contracts	0	0	18,686,000	0
Provision for/(benefit from) income taxes	36,855,000	36,945,000	83,017,000	92,412,000
Expenditures for additions to property & equipment, net of grants from outside parties	107,169,000	80,901,000	244,694,000	228,178,000
North American Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	314,563,000	345,092,000	943,167,000	966,476,000
Income/(loss) from operations	90,564,000	100,948,000	224,266,000	242,927,000
Depreciation and amortization	35,158,000	32,809,000	105,399,000	93,633,000
Interest expense, net	9,788,000	9,865,000	30,149,000	32,094,000
Loss on settlement of foreign currency forward purchase contracts			16,374,000
Provision for/(benefit from) income taxes	32,332,000	31,598,000	71,559,000	77,463,000
Expenditures for additions to property & equipment, net of grants from outside parties	86,620,000	73,159,000	205,330,000	212,058,000
Australian Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	61,013,000	81,478,000	187,763,000	240,889,000
Income/(loss) from operations	14,966,000	22,355,000	44,333,000	66,621,000
Depreciation and amortization	7,151,000	7,072,000	20,771,000	21,306,000
Interest expense, net	2,055,000	2,486,000	6,659,000	10,035,000
Loss on settlement of foreign currency forward purchase contracts			2,312,000
Provision for/(benefit from) income taxes	3,896,000	5,944,000	10,653,000	16,947,000
Expenditures for additions to property & equipment, net of grants from outside parties	6,354,000	7,661,000	20,128,000	15,541,000
U.K./European Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	170,723,000	5,973,000	354,618,000	16,020,000
Income/(loss) from operations	12,029,000	(187,000)	21,031,000	(1,448,000)
Depreciation and amortization	5,994,000	396,000	12,398,000	1,191,000
Interest expense, net	5,396,000	221,000	11,561,000	623,000
Loss on settlement of foreign currency forward purchase contracts			0
Provision for/(benefit from) income taxes	627,000	(597,000)	805,000	(1,998,000)
Expenditures for additions to property & equipment, net of grants from outside parties	$ 14,195,000	$ 81,000	$ 19,236,000	$ 579,000