Investment Securities (Summary Of Investment Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Schedule of Investments [Line Items]
Available for sale - Amortized cost	$ 3,181,393		$ 3,069,182
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	64,928		98,467
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(52,549)		(31,489)
Fair Value	3,193,772		3,136,160
Held-to-maturity - Carrying value	3,205,999		3,107,529
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	83,716		157,781
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(41,095)		(592)
Held to Maturity, Fair Value - Total debt securities	3,248,620		3,264,718
Total investment securities, Amortized Cost	6,387,392		6,176,711
Total investment securities, Recognized in OCI - Gross Unrealized Gains	64,928		98,467
Total investment securities, Recognized in OCI - Gross Unrealized Losses	(52,549)		(31,489)
Total investment securities, Carrying Value	6,399,771		6,243,689
Total investment securities, Not Recognized in OCI - Gross Unrealized Gains	83,716		157,781
Total investment securities, Not Recognized in OCI - Gross Unrealized Losses	(41,095)		(592)
Total investments securities, Fair Value	6,442,392		6,400,878
U.S. Treasury Bills [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	200		200
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	0		0
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	0		0
Fair Value	200		200
Agency CMOs [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	868,288		1,284,126
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	18,537		25,972
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(1,349)		(92)
Fair Value	885,476		1,310,006
Held-to-maturity - Carrying value	368,980		500,369
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	11,590		16,643
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(492)		(8)
Held to Maturity, Fair Value - Total debt securities	380,078		517,004
Agency MBS [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	1,318,550		1,121,941
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	9,120		21,437
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(34,416)		(1,098)
Fair Value	1,293,254		1,142,280
Held-to-maturity - Carrying value	2,095,513		1,833,677
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	48,495		88,082
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(35,832)		(474)
Held to Maturity, Fair Value - Total debt securities	2,108,176		1,921,285
Agency commercial mortgage-backed securities (ACMBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	19,988
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	96
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	0
Fair Value	20,084
CMBS [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	437,616		359,438
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	29,367		42,086
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(1,032)		(3,493)
Fair Value	465,951		398,031
Held-to-maturity - Carrying value	265,727		199,810
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	9,272		18,324
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(4,028)		0
Held to Maturity, Fair Value - Total debt securities	270,971		218,134
CLOs [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	333,023		88,765
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	637		0
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(1,126)		(225)
Fair Value	332,534		88,540
Pooled trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	36,581	[1]	46,018	[2]
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	0	[1]	0	[2]
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(6,617)	[1]	(19,811)	[2]
Fair Value	29,964	[1]	26,207	[2]
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	51,311		51,181
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	0		0
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(8,009)		(6,766)
Fair Value	43,302		44,415
Corporate debt securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	109,529		111,281
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	4,089		6,918
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	0		0
Fair Value	113,618		118,199
Equity securities - financial institutions [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	6,307	[3]	6,232	[4]
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	3,082	[3]	2,054	[4]
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	0	[3]	(4)	[4]
Fair Value	9,389	[3]	8,282	[4]
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Carrying value	466,084		559,131
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	14,135		34,366
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(743)		(110)
Held to Maturity, Fair Value - Total debt securities	479,476		593,387
Private Label MBS [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Carrying value	9,695		14,542
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	224		366
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	0		0
Held to Maturity, Fair Value - Total debt securities	$ 9,919		$ 14,908

[1] Amortized cost is net of $9.4 million of credit related other-than-temporary impairment at September 30, 2013.

[2] Amortized cost is net of $10.5 million of credit related other-than-temporary impairment at December 31, 2012.

[3] Amortized cost is net of $21.3 million of other-than-temporary impairment at September 30, 2013.

[4] Amortized cost is net of $21.3 million of other-than-temporary impairment at December 31, 2012.