Interest-Bearing Deposits - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Deposits [Abstract] | |||
| Interest-bearing demand deposit, money market | $ 779.2 | $ 580.8 | |
| Certificates of deposit in denominations of $100 thousand or more | 145.4 | 157.7 | |
| Interest expense related to certificates of deposit $100 thousand or greater | $ 1.2 | $ 1.8 | $ 3.7 |