Investment Securities (Summary Of Investment Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Investments [Line Items]
Available for sale - Amortized cost	$ 3,051,434	$ 2,849,463
Available for sale - Gross unrealized gains, Recognized in OCI	104,801	76,487
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(35,881)	(51,186)
Available for sale - Carrying value	3,120,354	2,874,764
Available for sale - Fair value	3,120,354	2,874,764
Held-to-maturity - Amortized cost	3,142,160	2,973,727
Held-to-maturity - Carrying value	3,142,160	2,973,727
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	179,448	156,993
Held-to-maturity - Gross unrealized losses, Not Recognized in OCI	(291)	(174)
Held-to-maturity - Fair value	3,321,317	3,130,546
Amortized cost	6,193,594	5,823,190
Gross unrealized gains, Recognized in OCI	104,801	76,487
Gross unrealized losses, Recognized in OCI	(35,881)	(51,186)
Carrying value	6,262,514	5,848,491
Gross unrealized gains, Not Recognized in OCI	179,448	156,993
Gross unrealized losses, Not Recognized in OCI	(291)	(174)
Fair value	6,441,671	6,005,310
U.S. Treasury Bills [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	200	200
Available for sale - Carrying value	200	200
Available for sale - Fair value	200	200
Agency CMOs - GSE [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	1,445,317	1,916,372
Available for sale - Gross unrealized gains, Recognized in OCI	29,168	27,211
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(275)	(3,341)
Available for sale - Carrying value	1,474,210	1,940,242
Available for sale - Fair value	1,474,210	1,940,242
Held-to-maturity - Amortized cost	567,941	733,889
Held-to-maturity - Carrying value	567,941	733,889
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	19,323	20,555
Held-to-maturity - Fair value	587,264	754,444
Corporate Debt [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	111,857
Available for sale - Gross unrealized gains, Recognized in OCI	6,281
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	0
Available for sale - Carrying value	118,138
Available for sale - Fair value	118,138
Pooled Trust Preferred Securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	49,583	52,606
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(21,330)	(23,608)
Available for sale - Carrying value	28,253	28,998
Available for sale - Fair value	28,253	28,998
Single Issuer Trust Preferred Securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	51,144	51,027
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(9,724)	(12,813)
Available for sale - Carrying value	41,420	38,214
Available for sale - Fair value	41,420	38,214
Equity Securities - Financial Institutions [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	6,232	7,669
Available for sale - Gross unrealized gains, Recognized in OCI	2,083	1,802
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(20)	(24)
Available for sale - Carrying value	8,295	9,447
Available for sale - Fair value	8,295	9,447
Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	1,042,266	502,389
Available for sale - Gross unrealized gains, Recognized in OCI	27,579	25,079
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(628)	(158)
Available for sale - Carrying value	1,069,217	527,310
Available for sale - Fair value	1,069,217	527,310
Held-to-maturity - Amortized cost	1,760,261	1,411,008
Held-to-maturity - Carrying value	1,760,261	1,411,008
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	103,840	98,449
Held-to-maturity - Gross unrealized losses, Not Recognized in OCI	(37)
Held-to-maturity - Fair value	1,864,064	1,509,457
CMBS [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	344,835	319,200
Available for sale - Gross unrealized gains, Recognized in OCI	39,690	22,395
Available-for-sale Securities, Gross Unrealized Losses, Recognized in OCI	(3,904)	(11,242)
Available for sale - Carrying value	380,621	330,353
Available for sale - Fair value	380,621	330,353
Held-to-maturity - Amortized cost	200,101	158,451
Held-to-maturity - Carrying value	200,101	158,451
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	17,926	6,588
Held-to-maturity - Gross unrealized losses, Not Recognized in OCI	(76)
Held-to-maturity - Fair value	217,951	165,039
Municipal Bonds And Notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Amortized cost	597,664	646,358
Held-to-maturity - Carrying value	597,664	646,358
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	37,915	30,960
Held-to-maturity - Gross unrealized losses, Not Recognized in OCI	(178)	(174)
Held-to-maturity - Fair value	635,401	677,144
Private Label MBS [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Amortized cost	16,193	24,021
Held-to-maturity - Carrying value	16,193	24,021
Held-to-maturity - Gross unrealized gains, Not Recognized in OCI	444	441
Held-to-maturity - Fair value	$ 16,637	$ 24,462

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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