Fair Values of Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Fair Value Measurements [Line Items]
Loans held for sale	$ 1,000,394,000		$ 719,496,000
Loans held for sale, lower of cost or fair value	831,197,000		524,120,000
Valuation allowance for OREO	0	79,000
Mortgage servicing rights, at carrying value	941,100,000
Mortgage servicing rights, at fair value	10,100,000
Mortgage servicing rights, sale closing date	Apr. 01, 2014
Level 2
Fair Value Measurements [Line Items]
Loans held for sale	1,000,394,000		719,496,000
Level 2 | Fair value, measurements, recurring
Fair Value Measurements [Line Items]
Loans held for sale	$ 169,200,000		$ 192,600,000