Mortgage Servicing Rights - Fair Value of Mortgage Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Loans [Member]	Dec. 31, 2012 Loans [Member]	Dec. 31, 2011 Loans [Member]	Dec. 31, 2010 Loans [Member]	Dec. 31, 2013 Mortgage servicing rights [Member]	Dec. 31, 2012 Mortgage servicing rights [Member]	Dec. 31, 2011 Mortgage servicing rights [Member]
Servicing Assets at Fair Value [Line Items]
Balance at beginning of period				$ 680,197	$ 666,512	$ 598,185	$ 573,300	$ 4,552	$ 4,603	$ 4,605
Additions								1,360	1,965	1,105
Change in fair value								253	(2,016)	(1,107)
Balance at end of period				680,197	666,512	598,185	573,300	6,165	4,552	4,603
Contractually specified servicing fees, late fees and ancillary fees earned	$ 1,774	$ 1,666	$ 1,495
Weighted-average prepayment speed (CPR)	10.30%	20.30%	19.30%
Weighted-average discount rate	10.00%	10.00%	9.00%