Unaudited Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Unaudited Consolidated Statements of Cash Flows [Abstract]
Net cash provided by operating activities	$ 9,160	$ 12,304
Investing activities:
Purchases of available-for-sale investments	(104,263)	(92,439)
Proceeds from sales or maturities of available-for-sale investments	108,087	113,044
Net sales (purchases) of short-term investments	(203)	461
Other investing activities	(2,808)	(16,678)
Net cash provided by investing activities	813	4,388
Financing activities:
Dividends paid to shareholders	(3,753)	(3,777)
Net cash used in financing activities	(3,753)	(3,777)
Effect of foreign exchange rates on cash and cash equivalents	(501)	(186)
Increase in cash and cash equivalents	5,719	12,729
Cash and cash equivalents at beginning of period	59,297	71,549
Cash and cash equivalents at end of period	$ 65,016	$ 84,278