Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 10,373	$ 5,732	$ 21,323	$ 14,113
Other comprehensive income (loss), net of taxes:
Cumulative translation adjustments	7,197	(2,593)	6,865	298
Changes in market value of investments:
Unrealized gain (loss), net of taxes of $188 and ($146) for the three months ended September 30, 2012 and 2011, and $354 and ($143) for the nine months ended September 30, 2012 and 2011	291	(197)	624	11
Less: reclassification adjustment for net gains realized in net income, net of taxes of $2 for the three months ended September 30, 2012, and $12 and $3 for the nine months ended September 30, 2012 and 2011	(3)		(17)	(4)
Net change in market value of investments	288	(197)	607	7
Other comprehensive income (loss)	7,485	(2,790)	7,472	305
Comprehensive income	$ 17,858	$ 2,942	$ 28,795	$ 14,418