Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Consolidated Statements Of Comprehensive Income (Loss) [Abstract]
Net income	$ 70,146	[1]	$ 41,133	[2]	$ 5,771
Unrealized losses on interest rate swap contracts, net of income taxes of $11,219 and $1,383 in 2011 and 2010, respectively	(18,283)		(5,286)		(1,046)
Foreign currency translation adjustments	(566)		(2,149)		7,453
Other comprehensive (loss) income	(18,849)		(7,435)		6,407
Total comprehensive income	51,297		33,698		12,178
Less: comprehensive (loss) income attributable to noncontrolling interests	(306)		261		540
Comprehensive income attributable to controlling interests	$ 51,603		$ 33,437		$ 11,638

[1] Includes $37.0 million of tax benefit recorded in the quarter ended September 30 as a result of a tax reporting change with respect to the Company's U.K. operations.

[2] Includes release of $23.7 million and $3.5 million in previously-recognized valuation allowances related to the Company's United States segment for the quarters ended September 30 and December 31, respectively. Additionally, the quarter ended September 30 includes pre-tax charges of approximately $14.5 million related to certain charges associated with the refinancing of the Company's outstanding debt obligations.