Borrowed Funds (Detail) - Unused Short-Term Credit Lines Available for Use - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
FRBs Discount Window Primary Credit Program	$ 655,745	$ 675,507
Available federal funds lines	659,000	685,500
Notes Payable to Banks
Short-term Debt [Line Items]
Correspondent bank line of credit	$ 0	$ 35,000