Investment Securities (Summary Of Investment Securities) (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain]
Schedule of Investments [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 10,460	$ (10,500)
Accumulated Other-than-Temporary Impairment [Member]
Schedule of Investments [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 21,300	$ 21,300