Note Borrowings (Notes payable) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Others	$ 17,904	$ 18,642
Notes payable	1,744,687	1,536,356
Advances due 2018 To 2029 with fixed Rates 0.89% to 4.19%
Debt Instrument [Line Items]
Advances with the FHLB	567,031	572,307
Floating Rate from of 0.34% over the 1 month LIBOR with maturities on 2019
Debt Instrument [Line Items]
Advances with the FHLB	13,000	34,164
Floating Rate from 0.12% to 0.24% over the 3 month LIBOR with maturities on 2019
Debt Instrument [Line Items]
Advances with the FHLB	19,724	25,019
Fixed Rate from 6.125% to 7.00% Percent Notes paying interest semiannually, net of debt issuance costs of $7,841
Debt Instrument [Line Items]
Long Term Debt	742,159	446,873
Fixed Rate 6.125% to 6.7% Junior Subordinated Deferrable Interest Debentures Due 2033 to 2034, net of debt issuance costs of $429
Debt Instrument [Line Items]
Long Term Debt	$ 384,869	$ 439,351