Debt and Equity Securities (Net Unrealized Gains (Losses) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized gains (losses)	$ 13,767	$ (4,833)
Debt Securities for Which an OTTI Has Been Recognized
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized gains (losses)	324	(625)
Debt Securities-All Other
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized gains (losses)	3,960	(28,152)
Equity Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized gains (losses)	$ 9,483	$ 23,944