Borrowings (Advances from FHLB and Respective Maturity Schedule) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Maturity:
One Year	$ 250,000,000	$ 210,000,000
Two Years	0	0
Three Years	75,000,000	0
Four Years	160,000,000	75,000,000
Five Years	80,000,000	160,000,000
After five years	90,000,000	170,000,000
Total advances from FHLB	$ 655,000,000	$ 615,000,000
Maturity:
One Year	0.20%	0.18%
Two Years	0.00%	0.00%
Three years	3.48%	0.00%
Four years	2.45%	3.48%
Five years	3.50%	2.45%
After five years	3.53%	3.52%
Total advances from FHLB	1.99%	2.09%