Federal Home Loan Bank Advances (Summary Of Advances Payable To The Federal Home Loan Bank) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Outstanding	$ 1,627,444	$ 1,827,527
Weighted Average Contractual Coupon Rate	0.60%	0.59%
Unamortized premiums	73	85
Total Federal Home Loan Bank advances	1,627,517	1,827,612
2013 [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Outstanding	1,125,000	1,425,000
Weighted Average Contractual Coupon Rate	0.22%	0.34%
2016 [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Outstanding	145,934	145,934
Weighted Average Contractual Coupon Rate	1.80%	1.80%
2017 [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Outstanding	500	500
Weighted Average Contractual Coupon Rate	5.66%	5.66%
2018 - 2032 [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Outstanding	$ 356,010	$ 256,093
Weighted Average Contractual Coupon Rate	1.33%	1.29%