Investments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 Securities Individual Equity	Dec. 31, 2012
Investment [Line Items]
Short term debt	$ 84,422,000	$ 68,924,000
Carrying value of investments	10,600,000
Held to maturity investments	16,300,000
Individual fixed maturity held in unrealized loss position	182
Equity securities held in unrealized loss position	8
Individual fixed maturity held in unrealized loss position	18
Number of equity securities to be deemed other-than-temporarily impaired	4
Equity securities [Member]
Investment [Line Items]
Impairment losses recognized	2,200,000
Corporate bonds [Member]
Investment [Line Items]
Short term debt	82,700,000	63,500,000
Certificates of deposit [Member]
Investment [Line Items]
Short term debt	900,000	900,000
Municipal securities [Member]
Investment [Line Items]
Short term debt	$ 800,000	$ 4,500,000