Debentures Payable - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Jul. 30, 2012
Debt Instrument [Line Items]
Preferred stock shares issued by unconsolidated trust	40,000
Common stock shares issued by unconsolidated trust	1,240
Price of preferred and common shares issued by unconsolidated trust	$ 1,000
Proceeds to unconsolidated trust from issuance of junior subordinated debenture sale of preferred stock shares	$ 41.2
Maturity date	Jul. 30, 2037
Interest rate	3.986%
Period for deferral of preferred securities dividend	5 years
Unamortized debt discount	$ 0.9
Junior Subordinated Debentures [Member]
Debt Instrument [Line Items]
Debentures paid fixed rate		9.277%
Variable rate	Three-Month LIBOR plus 375 basis points
Variable rate basis point	3.75%