Unaudited Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Unaudited Consolidated Statements of Cash Flows [Abstract]
Net cash provided by operating activities	$ 12,304	$ 11,666
Investing activities:
Purchases of available-for-sale investments	(92,439)	(104,714)
Purchases of limited partnership interests	0	(1,538)
Proceeds from sales or maturities of available-for-sale investments	113,044	78,829
Net sales of short-term investments	461	382
Other investing activities	(16,678)	3,552
Net cash provided by (used in) investing activities	4,388	(23,489)
Financing activities:
Dividends paid to shareholders	(3,777)	(3,749)
Net cash used in financing activities	(3,777)	(3,749)
Effect of foreign exchange rates on cash and cash equivalents	(186)	204
Increase (decrease) in cash and cash equivalents	12,729	(15,368)
Cash and cash equivalents at beginning of period	71,549	89,726
Cash and cash equivalents at end of period	$ 84,278	$ 74,358