Note Borrowings (Borrowings by contractual maturities) (Detail) $ in Thousands	Sep. 30, 2017 USD ($)
Debt Disclosure [Line Items]
2017	$ 403,449
2018	464,176
2019	608,530
2020	112,088
2021	21,694
Later years	537,127
Borrowed Funds	2,147,064
Assets Sold Under Agreements To Repurchase
Debt Disclosure [Line Items]
2017	165,315
2018	209,090
2019	0
2020	0
2021	0
Later years	0
Borrowed Funds	374,405
Other Short Term Borrowings
Debt Disclosure [Line Items]
2017	205,598
2018	35,000
2019	0
2020	0
2021	0
Later years	0
Borrowed Funds	240,598
Notes Payable
Debt Disclosure [Line Items]
2017	32,536
2018	220,086
2019	608,530
2020	112,088
2021	21,694
Later years	537,127
Borrowed Funds	$ 1,532,061