Segments and Operations by Geographic Area (Reconciliation of EBITDA to Income from Continuing Operations) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting, Reconciling Item [Line Items]
Interest expense, net	$ (11,838,000)	$ (9,487,000)	$ (21,883,000)	$ (18,438,000)
Depreciation			(65,355,000)	(42,946,000)
Amortization			(9,400,000)	(5,700,000)
Income from continuing operations before provision for income taxes	57,307,000	51,112,000	88,975,000	70,610,000
Segment, Continuing Operations [Member]
Segment Reporting, Reconciling Item [Line Items]
EBITDA	102,700,000	82,400,000	176,200,000	131,500,000
Interest expense, net	(11,800,000)	(9,500,000)	(21,900,000)	(18,400,000)
Depreciation	(33,602,000)	(21,763,000)	(65,355,000)	(42,480,000)
Amortization	(5,300,000)	(2,800,000)	(9,400,000)	(5,700,000)
Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting, Reconciling Item [Line Items]
Depreciation	$ (28,300,000)	$ (18,900,000)	$ (55,900,000)	$ (36,800,000)