Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 46,446	$ 70,803	$ 191,732	$ 198,320
Change in fair value of interest rate swap contracts
Unrealized holding losses arising during the period on effective hedges, net of income tax benefit of $9 and $252, respectively		(16)		(446)
Less: Reclassification adjustments for losses included in net income, net of income taxes of $999 and $4,852, respectively		1,773		8,608
Change in fair value of interest rate swap contracts, net		1,757		8,162
Foreign currency translation adjustment during the period	732	(1,107)	565	(610)
Unrealized holding gains (losses) on corporate debt securities arising during the period	49	(546)	134	364
Other comprehensive income	781	104	699	7,916
Comprehensive income	$ 47,227	$ 70,907	$ 192,431	$ 206,236