XML 48 R37.htm IDEA: XBRL DOCUMENT v3.8.0.1
Securities - Company's Book Value of Pledged Securities (Detail) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Pledged Financial Instruments Not Separately Reported Securities Pledged By Type Of Security [Abstract]    
Book value of pledged securities $ 398,605 $ 439,692