Borrowed Funds - Schedule of FHLB Repayment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2017	$ 795,000
2018	50,000
Long-term borrowings [Member]
Debt Instrument [Line Items]
2016	184,636
2017	97,960
2018	354,995
Thereafter	635,000
Total long-term FHLB advances	$ 1,272,591	$ 1,832,166