Effect of Derivative Instruments on Consolidated Statements of Income and Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
(Loss) Gain Included in Mortgage Banking Income	$ (6,211)	$ 3,913	$ 6,056	$ 2,990
Treasury Options
Derivative Instruments, Gain (Loss) [Line Items]
(Loss) Gain Included in Mortgage Banking Income	(6,245)	2,485	3,619	(2,589)
Eurodollar Futures
Derivative Instruments, Gain (Loss) [Line Items]
(Loss) Gain Included in Mortgage Banking Income	17	1,134	(38)	1,495
Swaps
Derivative Instruments, Gain (Loss) [Line Items]
(Loss) Gain Included in Mortgage Banking Income	(1,751)		2,427
Forward commitments to buy/sell loans/mortgage-backed securities
Derivative Instruments, Gain (Loss) [Line Items]
(Loss) Gain Included in Mortgage Banking Income	$ 1,768	$ 294	$ 48	$ 4,084