Segments and Operations by Geographic Area Segments and Operations by Geographic Area (Reconciliation of EBITDA to Consolidated Income) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense, net	$ (37,376,000)	$ (34,466,000)	$ (29,178,000)
Amortization	(12,200,000)	(13,900,000)
Income from continuing operations before provision for income taxes	192,719,000	159,280,000	114,072,000
Segment, Continuing Operations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
EBITDA	322,100,000	267,900,000	200,100,000
Interest expense, net	(37,376,000)	(34,466,000)	(29,178,000)
Depreciation	(79,800,000)	(60,200,000)	(44,000,000)
Amortization	$ (12,200,000)	$ (13,900,000)	$ (12,900,000)