Additional Information Related to Income Statement (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Interest income	$ 964	$ 765	$ 1,066
Interest expense	(240)	(378)	(601)
Other-than-temporary impairment on securities	(11)	(10)	(86)
Realized gains on investments	3	52	1,080
Realized losses on investments	(60)		(51)
Equity in earnings of unconsolidated affiliates		41	25
Net investment income and other	$ 656	$ 470	$ 1,433