Investment Securities (Summary Of Investment Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Schedule of Investments [Line Items]
Available for sale - Amortized cost	$ 3,253,001		$ 3,069,182
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	63,117		98,467
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(58,758)		(31,489)
Available for sale - Fair Value	3,257,360		3,136,160
Held-to-maturity - Carrying value	3,129,864		3,107,529
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	88,027		157,781
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(43,743)		(592)
Held to Maturity, Fair Value - Total debt securities	3,174,148		3,264,718
Total investment securities, Amortized Cost	6,382,865		6,176,711
Total investment securities, Recognized in OCI - Gross Unrealized Gains	63,117		98,467
Total investment securities, Recognized in OCI - Gross Unrealized Losses	(58,758)		(31,489)
Total investment securities, Carrying Value	6,387,224		6,243,689
Total investment securities, Not Recognized in OCU - Gross Unrealized Gains	88,027		157,781
Total investment securities, Not Recognized in OCI - Gross Unrealized Losses	(43,743)		(592)
Total investments securities, Fair Value	6,431,508		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
Available for sale - Fair Value	200		200
Agency collateralized mortgage obligations (CMOs) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	988,928		1,284,126
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	15,696		25,972
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(727)		(92)
Available for sale - Fair Value	1,003,897		1,310,006
Held-to-maturity - Carrying value	401,617		500,369
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	12,112		16,643
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(801)		(8)
Held to Maturity, Fair Value - Total debt securities	412,928		517,004
Agency mortgage-backed securities (MBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	1,362,955		1,121,941
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	11,549		21,437
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(36,312)		(1,098)
Available for sale - Fair Value	1,338,192		1,142,280
Held-to-maturity - Carrying value	1,984,849		1,833,677
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	49,697		88,082
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(37,413)		(474)
Held to Maturity, Fair Value - Total debt securities	1,997,133		1,921,285
Commercial mortgage-backed securities (CMBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	411,544		359,438
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	29,489		42,086
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(897)		(3,493)
Available for sale - Fair Value	440,136		398,031
Held-to-maturity - Carrying value	245,475		199,810
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	8,789		18,324
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(5,167)		0
Held to Maturity, Fair Value - Total debt securities	249,097		218,134
Collateralized loan obligations (CLOs) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	277,657		88,765
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	825		0
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(474)		(225)
Available for sale - Fair Value	278,008		88,540
Pooled trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	44,025	[1],[2]	46,018	[3]
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	0	[1]	0	[3]
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(13,810)	[1]	(19,811)	[3]
Available for sale - Fair Value	30,215	[1]	26,207	[3]
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	51,267		51,181
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	0		0
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(6,392)		(6,766)
Available for sale - Fair Value	44,875		44,415
Corporate debt securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	110,118		111,281
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	2,699		6,918
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	(146)		0	[4]
Available for sale - Fair Value	112,671		118,199
Equity securities - financial institutions [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	6,307	[5]	6,232	[4]
Available-for-sale - Recognized in OCI - Gross Unrealized Gains	2,859	[5]	2,054	[4]
Available-for-sale - Recognized in OCI - Gross Unrealized Losses	0	[5]	(4)	[4]
Available for sale - Fair Value	9,166	[5]	8,282	[4]
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Carrying value	486,862		559,131
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	17,165		34,366
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	(362)		(110)
Held to Maturity, Fair Value - Total debt securities	503,665		593,387
Private Label MBS [Member]
Schedule of Investments [Line Items]
Held-to-maturity - Carrying value	11,061		14,542
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	264		366
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	0		0
Held to Maturity, Fair Value - Total debt securities	$ 11,325		$ 14,908

[1] Amortized cost is net of $10.5 million of credit related other-than-temporary impairment at June 30, 2013.

[2] For the securities previously deemed impaired, the amortized cost is reflective of previous OTTI recognized in earnings.

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

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

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