Advances from FHLB and Respective Maturity Schedule (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Maturity:
One year	$ 35,058	$ 350
Two years	0	58
Three years	0	0
Four years	45,000	0
Five years	85,000	160,000
After five years	280,000	245,000
Total advances from FHLB	$ 440,058	$ 405,408
Maturity:
One year	0.36%	0.37%
Two years	0.00%	4.13%
Three years	0.00%	0.00%
Four years	4.47%	0.00%
Five years	3.57%	4.51%
After five years	2.91%	2.84%
Total advances from FHLB	2.97%	2.99%