Note Borrowings (Other short-term borrowings and maximum aggregate balance of short term borrowings) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Other Borrowings	$ 1,200	$ 1,208
Total other short-term borrowings	186,200	96,208
Advances paying interest ranging from 1.63% to 2.02%
Short-term Debt [Line Items]
Advances with the FHLB paying interest at maturity	$ 185,000	$ 95,000