Troubled Debts Restructured Defaulted (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Residential Mortgage Investment	Dec. 31, 2011 Consumer loans Other Investment	Dec. 31, 2012 Defaulted Loans Commercial Real estate Investment	Dec. 31, 2012 Defaulted Loans Commercial Other Investment	Dec. 31, 2012 Defaulted Loans Residential Mortgage Investment	Dec. 31, 2012 Defaulted Loans Consumer loans Other Investment
Financing Receivable, Modifications [Line Items]
No. of Loans	3	2	1	1	2	1
Post-Modification Outstanding Recorded Balance	$ 733	$ 48	$ 109	$ 518	$ 61	$ 14