Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
NET INCOME	$ 37,388	$ 28,625	$ 59,506	$ 51,742
Other comprehensive loss, net of taxes:
Foreign currency translation adjustment	(19,268)	(1,400)	(26,724)	(6)
Unrealized gain on marketable securities, net of tax provision of $0, $3, $0 and $5, respectively	0	5	0	8
Net unrealized gain (loss) on interest rate swaps:
Unrealized gain (loss) arising during the period, net of tax benefit (provision) of ($4,622), $4,273, ($4,614) and $4,566, respectively	7,704	(7,122)	7,690	(7,610)
Reclassification adjustment for loss included in interest expense, net of tax provision of $1,020, $1,076, $2,045 and $2,210, respectively	1,701	1,793	3,409	3,684
Net unrealized gain (loss) on interest rate swaps, net of tax	9,405	(5,329)	11,099	(3,926)
OTHER COMPREHENSIVE LOSS, NET OF TAXES	(9,863)	(6,724)	(15,625)	(3,924)
COMPREHENSIVE INCOME	27,525	21,901	43,881	47,818
Total [Member]
Statement of Other Comprehensive Income [Abstract]
NET INCOME	$ 37,388	$ 28,625	$ 59,506	$ 51,742