Effect of Derivative Instruments on Consolidated Statements of Income and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Included in Mortgage Banking Income	$ 4,653	$ 18,526	$ 7,694	$ 23,932
Treasury Options
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Included in Mortgage Banking Income	1,454	(3,368)	1,055	(6,956)
Eurodollar Futures
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Included in Mortgage Banking Income	161	(11)	106	4
Forward commitments to buy/sell loans/mortgage-backed securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Included in Mortgage Banking Income	$ 3,038	$ 21,905	$ 6,533	$ 30,884