Interest-Bearing Deposits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deposits [Abstract]
Interest-bearing demand deposit, money market	$ 556.7	$ 581.5
Certificates of deposit in denominations of $100 thousand or more	464.7	322.4
Interest expense related to certificates of deposit $100 thousand or greater	$ 4.7	$ 5.3	$ 7.4