Other Real Estate Owned - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Real Estate Properties [Line Items]
Percentage covered up to $467.2 million	0.00%
Losses up to $275.0 [Member]
Real Estate Properties [Line Items]
Loss sharing agreements amount, 80% on assets acquired	$ 275.0
Loss sharing reimbursement threshold	80.00%
Losses in Excess of $275.0 up to $467.2 [Member]
Real Estate Properties [Line Items]
Zero percent for losses on acquisition	467.2
Losses in Excess of $467.2 [Member]
Real Estate Properties [Line Items]
Loss sharing agreements amount, 80% on assets acquired	$ 467.2
Loss sharing reimbursement threshold	80.00%