Note Borrowings (Borrowings by contractual maturities) (Detail) $ in Thousands	Mar. 31, 2017 USD ($)
Debt Disclosure [Line Items]
2017	$ 514,768
2018	210,281
2019	597,793
2020	112,237
2021	21,694
Later years	537,113
Borrowed Funds	1,993,886
Assets Sold Under Agreements To Repurchase
Debt Disclosure [Line Items]
2017	434,714
2018	0
2019	0
2020	0
2021	0
Later years	0
Borrowed Funds	434,714
Other Short Term Borrowings
Debt Disclosure [Line Items]
2017	1,200
2018	0
2019	0
2020	0
2021	0
Later years	0
Borrowed Funds	1,200
Notes Payable
Debt Disclosure [Line Items]
2017	78,854
2018	210,281
2019	597,793
2020	112,237
2021	21,694
Later years	537,113
Borrowed Funds	$ 1,557,972