Condensed Consolidated Statement 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
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 35,967	$ 31,188	$ 58,738	$ 59,727
Foreign currency translation adjustment, net of tax (benefit) of ($264) and $(978) for the three and six months of 2013, respectively, and ($431) and $7 for the three and six months of 2012, respectively	(363)	(1,430)	(2,116)	24
Unrealized gain (loss) on available-for-sale investments, net of tax (benefit) of $1,287 and $2,915 for the three and six months of 2013, respectively, and ($17) and $48 for the three and six months of 2012, respectively	2,180	(26)	5,001	72
Other Comprehensive Income (Loss), Net of Tax	1,817	(1,456)	2,885	96
Comprehensive Income	37,872	29,732	61,869	59,823
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	37,784	29,732	61,623	59,823
Net Income (Loss) Attributable to Noncontrolling Interest	(73)	0	(224)	0
Foreign currency translation adjustment attributable to noncontrolling Interest, net of tax (benefit) of ($11) and ($17) for the three and six months of 2013, respectively, and zero and zero for the three and six months of 2012 , respectively	$ (15)	$ 0	$ (22)	$ 0