Available-For-Sale Securities (Schedule Of Available-For-Sale Securities Portfolio Continuous Unrealized Loss Position) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	$ 273,972
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(6,727)
Continuous unrealized losses existing for greater than 12 months, Fair value	82,549
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(4,076)
Total, Fair value	356,521
Total, Unrealized losses	(10,803)
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	0
Continuous unrealized losses existing for less than 12 months, Unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	0
Total, Unrealized losses	0
U.S. Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	216,383
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(2,374)
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	216,383
Total, Unrealized losses	(2,374)
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	14,177
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(22)
Continuous unrealized losses existing for greater than 12 months, Fair value	711
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(1)
Total, Fair value	14,888
Total, Unrealized losses	(23)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	21,248
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(1,095)
Continuous unrealized losses existing for greater than 12 months, Fair value	81,838
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(4,075)
Total, Fair value	103,086
Total, Unrealized losses	(5,170)
Corporate Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	0
Continuous unrealized losses existing for less than 12 months, Unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	0
Total, Unrealized losses	0
Mortgage Backed Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	0
Continuous unrealized losses existing for less than 12 months, Unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	0
Total, Unrealized losses	0
Mortgage-Backed, Non-Agency CMOs [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	0
Continuous unrealized losses existing for less than 12 months, Unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	0
Total, Unrealized losses	0
Other equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	22,164
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(3,236)
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	22,164
Total, Unrealized losses	$ (3,236)