Note Borrowings (Borrowings by contractual maturities) (Detail) $ in Thousands	Mar. 31, 2018 USD ($)
Debt Disclosure [Line Items]
2018	$ 808,896
2019	649,382
2020	112,069
2021	21,840
2022	5,143
Later years	533,135
Borrowed Funds	2,130,465
Assets Sold Under Agreements To Repurchase
Debt Disclosure [Line Items]
2018	380,061
2019	0
2020	0
2021	0
2022	0
Later years	0
Borrowed Funds	380,061
Other Short Term Borrowings
Debt Disclosure [Line Items]
2018	186,200
2019	0
2020	0
2021	0
2022	0
Later years	0
Borrowed Funds	186,200
Notes Payable
Debt Disclosure [Line Items]
2018	242,635
2019	649,382
2020	112,069
2021	21,840
2022	5,143
Later years	533,135
Borrowed Funds	$ 1,564,204