Available-For-Sale Securities (Schedule Of Available-For-Sale Securities Reconciliation) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 1,852,585		$ 1,785,113		$ 1,243,376
Gross unrealized gains	12,436		20,556		24,195
Gross unrealized losses	(83,138)		(9,593)		(10,803)
Available-for-sale securities, at fair value	1,781,883		1,796,076		1,256,768
US Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	225,190		220,226		25,045
Gross unrealized gains	150		198		211
Gross unrealized losses	(14,438)		(937)		0
Available-for-sale securities, at fair value	210,902		219,487		25,256
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	954,050		986,186		626,725
Gross unrealized gains	2,213		4,839		3,833
Gross unrealized losses	(43,574)		(986)		(2,374)
Available-for-sale securities, at fair value	912,689		990,039		628,184
Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	152,010		107,868		96,696
Gross unrealized gains	1,983		2,899		2,711
Gross unrealized losses	(3,346)		(296)		(23)
Available-for-sale securities, at fair value	150,647		110,471		99,384
Corporate Notes and Other, Financial Issuers [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	132,320		142,205		142,158
Gross unrealized gains	2,252		2,452		2,550
Gross unrealized losses	(2,513)		(3,982)		(5,170)
Available-for-sale securities, at fair value	132,059		140,675		139,538
Corporate Notes and Other, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	7,011		13,911		17,200
Gross unrealized gains	126		220		251
Gross unrealized losses	(15)		0		0
Available-for-sale securities, at fair value	7,122		14,131		17,451
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	268,166	[1]	188,485	[1]	225,393	[1]
Gross unrealized gains	4,157	[1]	8,805	[1]	13,733	[1]
Gross unrealized losses	(12,861)	[1]	(30)	[1]	0	[1]
Available-for-sale securities, at fair value	259,462	[1]	197,260	[1]	239,126	[1]
Mortgage-Backed, Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	60,001	[1]	73,386	[1]	66,422	[1]
Gross unrealized gains	458	[1]	928	[1]	690	[1]
Gross unrealized losses	(728)	[1]	0	[1]	0	[1]
Available-for-sale securities, at fair value	59,731	[1]	74,314	[1]	67,112	[1]
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	53,837		52,846		43,737
Gross unrealized gains	1,097		215		216
Gross unrealized losses	(5,663)		(3,362)		(3,236)
Available-for-sale securities, at fair value	$ 49,271		$ 49,699		$ 40,717

[1] Consisting entirely of residential mortgage-backed securities, none of which are subprime.