Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Unaudited Consolidated Statements of Cash Flows [Abstract]
Net cash provided by operating activities	$ 1,973	$ 10,674
Investing activities:
Purchases of available-for-sale investments	(112,301)	(126,146)
Proceeds from sales or maturities of available-for-sale investments	89,042	104,555
Net sales of short-term investments	5	(3)
Other investing activities	(1,154)	(244)
Net cash used in investing activities	(24,408)	(21,838)
Financing activities:
Dividends paid to shareholders	(3,977)	(3,776)
Net cash used in financing activities	(3,977)	(3,776)
Effect of foreign exchange rates on cash and cash equivalents	419	(779)
Decrease in cash and cash equivalents	(25,993)	(15,719)
Cash and cash equivalents at beginning of period	73,538	64,632
Cash and cash equivalents at end of period	$ 47,545	$ 48,913