Deposits - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deposits [Abstract]
Certificates of deposits of $250,000 or more, maturities within one year	$ 182.8	$ 137.8
Certificates of deposits of $250,000 or more, maturities after one year	7.1	11.4
Certificates of deposits of $250,000 or more, total	189.9	149.2
Certificates of deposit of less than $ 250,000, maturities within one year	416.3	292.5
Certificates of deposit of less than $ 250,000, maturities after one year	23.2	28.5
Certificates of deposit of less than $250,000, total	$ 439.5	$ 321.0