Unaudited Consolidated Statements of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Unaudited Consolidated Statements of Cash Flows [Abstract]
Net cash provided by operating activities	$ 44,589	$ 36,857
Investing activities:
Purchases of long-term investments	(258,365)	(297,065)
Proceeds from sales or maturities of long-term investments	247,322	241,158
Net purchases of short-term investments	(919)	(711)
Other investing activities	(1,565)	(2,524)
Net cash used in investing activities	(13,527)	(59,142)
Financing activities:
Dividends paid to shareholders	(11,150)	(14,770)
Repayment on line of credit	(5,000)	(3,000)
Net cash used in financing activities	(16,150)	(17,770)
Effect of foreign exchange rates on cash and cash equivalents	(421)	152
Increase (decrease) in cash and cash equivalents	14,491	(39,903)
Cash and cash equivalents at beginning of period	38,223	79,504
Cash and cash equivalents at end of period	$ 52,714	$ 39,601