Borrowed Funds - Schedule of Long-Term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total long-term borrowings	$ 1,433,906	$ 1,810,728
Unamortized prepayment penalties and other purchase accounting adjustments	18,300	3,600
Deferred issuance costs	1,900	2,200
Long-term borrowings
Debt Instrument [Line Items]
FHLB advances, net	1,031,666	1,272,591
Securities sold under agreements to repurchase	165,000	307,500
Subordinated debt, net	236,731	230,573
Other	509	64
Total long-term borrowings	$ 1,433,906	$ 1,810,728