Fair Value Measurement of Assets and Liabilities - Assets and Liabilities Measured at Fair Value on Recurring and Non-Recurring Basis Non-Printing (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Unpaid principal balances of loans held for sale	$ 3.5	$ 16.9